Chocolate Hazelnut Praline Log Cake

 I am very excited to have my first partnership with Ninja Kitchen Singapore to introduce their Ninja Foodi Power Blender Ultimate System! It is really timely to be receiving their system near Christmas as I intend to make chocolate hazelnut praline log cakes for my family and friends!  

Bear with me as this will be a long post because the log cake consist of four different components, excluding my sugar-free snowman marshmallow decorations.

The four components of the log cake: chocolate hazelnut chiffon cake, hazelnut feuilletine crunch, hazelnut praline diplomat cream and dark chocolate ganache 

I used the blender system to make three items essential for the bake: hazelnut flour, finely chopped hazelnut and hazelnut praline paste. Toasted hazelnuts are used for all hazelnut related items in the cake as it is more aromatic.

Finely chopped hazelnut, hazelnut flour and hazelnut praline paste 

I love the fact that the blender is easy to use and clean! You may use my promo code: PSCB402 to enjoy $150 off original price of $499! Visit Ninja Kitchen Singapore's website if you would like to make the purchase.

Some items in the log cake can be prepared in advance to make the bake easier. Make sure you plan ahead of time the sequence of making the components as you want to make sure everything is ready when you assemble. I will be sharing the recipes in the order that you should be preparing. The portions suggested in this post is enough for two log cakes so scale ingredient portions accordingly.

The source of my inspiration and reference recipes for some components of the log cake are taken from here and here.

HAZELNUT FLOUR & FINELY CHOPPED HAZELNUT 

Ingredients:

150g blanched whole hazelnuts*

* Toast a total of 330-350g hazelnuts for the whole bake but you will only use a portion of it as flour and chopped nuts.

Steps:

1. Preheat oven to 160C fan/175C top and bottom heat only. Line large baking tray with parchment paper/Teflon sheet/silicone mat.

2. Bake hazelnuts in a single layer for 10 min or until lightly browned and aromatic. Adjust temperature and time accordingly as each oven is different.

3. Cool completely before using coffee grinder or blender to pulse the toasted nuts (about 120-150g) a few times until you have a good mix of finely chopped pieces and flour. Do not run the blender for too long or it may become a paste. Split the batch of hazelnuts into two if your blender/grinder is small. I used the Coffee & Spice Grinder of the Ninja Foodi Power Blender Ultimate System for this.

4. Use a sieve to sift the flour from the chopped pieces. I didn't use my superfine sieve for this as I want my chopped nuts portion to contain only chopped bits without the flour. The flour portion may not be superfine here but it is OK as an addition in the log cake. You may use a fine sieve to sift the coarse flour if you want superfine flour.

Prepare the flour and chopped nuts ahead of time. Store airtight in cool dry place if using within a week. Store in fridge or freezer for longer storage.

HAZELNUT PRALINE PASTE

Ingredients:

180g toasted hazelnuts (see above for toasting)

120g sugar

25g water

1/4 tsp salt

1 tbs (12g) oil of choice (I used peanut)

Steps:

1. Make caramel by heating sugar and water in a light coloured, heavy bottomed saucepan. Do not stir the syrup. Gently swirl the saucepan to mix evenly if need be. The darker the caramel colour, the deeper the flavour but be careful not to burn it! Once you have achieved a deep amber colour, remove from heat and pour the caramel onto baking tray lined with Teflon sheet/silicone mat.

2. Let the caramel cool completely before breaking it up into shards. You may use your hands or use a knife to chop it up. 

3. Put the caramel shards, toasted hazelnuts, salt and oil into blender. Blend until you get a paste. I used the Power Smoothie Bowl to make the paste. It is up to your personal preference to blend until it is completely smooth or still retains some coarse bits. I prefer my praline paste to have a little bite so I didn't blend until it is completely smooth.

Hazelnut praline is typically made by stirring the caramel and toasted nuts together before pouring it out onto the tray. I skipped this step to simplify the process as it is not necessary here. You only need to coat the hazelnuts with caramel if you are making praline shards.

Prepare the praline paste ahead of time. Store the praline paste in an airtight container at a cool and dry place until use if you are using it within the next couple of days. Store in the fridge for two-three weeks or in the freezer for longer storage.

You may refer to my Instagram reel to see how I made the hazelnut flour, chopped hazelnut and hazelnut praline paste:

https://www.instagram.com/reel/CmWUrlDgtvK/?igshid=NTdlMDg3MTY=

HAZELNUT PRALINE DIPLOMAT CREAM

Ingredients:

2 large egg yolks (62-65g eggs with shells on)

15-18g cornstarch/cornflour (use more if you prefer a thicker cream)

20g sugar*

Pinches of salt

240g milk

10g unsalted butter, softened

40g hazelnut praline paste 

1/2-1 tsp vanilla bean paste/extract

100g double cream/heavy cream/ non-dairy whipping cream (I used a combination of 25g double cream and 75g non-dairy whipping cream)**

* I used Allulose, a sugar replacement, so that the bake is slightly more diabetic friendly. You may use regular sugar and also adjust according to taste. I made the cream less sweet to suit the taste buds of my recipients.

** You may use your preferred choice of whipping cream. I used a combination to get the stability of non-dairy whipping cream in tropical climate like Singapore, and great milky taste of double cream. Be careful not to over whip dairy creams. You may want to add some sugar and stabilize with gelatin if using dairy cream only. I loosened cold double cream with a hand whisk before folding in non-dairy cream what was whipped until stiff. Non-dairy creams are pre-sweetened so I didn't add any sugar.

Steps:

1. Make the pastry cream. Heat milk in a saucepan until steaming hot but not boiling. In the meantime, whisk together egg yolks, sugar, salt and cornstarch in a heavy bowl until smooth.

2. Once milk is hot, pour in a thin stream into egg yolk mixture while whisking the egg yolk mix continuously. Pour everything back into saucepan and cook over medium-low heat while whisking continuously.  Pay attention to the custard as it will start to thicken suddenly. If it thickens up too fast, just remove from heat and keep whisking until smooth before putting it back on the stove. Continue cooking and whisking until mixture just starts to bubble. Cook for another 1 min while whisking continuously. 

3. Remove from heat. Add vanilla, praline paste and butter, one item at a time, whisking after each addition. 

4. Pour into a tray/bowl. Press cling wrap onto surface of pastry cream. Refrigerate for at least 2 hours or overnight. You may prepare the pastry cream a day in advance.

5. When it is time to assemble the log cake before you make the hazelnut feuilletine crunch, make the diplomat cream. To do so, take the pastry cream from fridge and loosen it by briefly whisking until smooth. Prepare whipped cream of choice. Fold into loosened pastry cream in three additions. Keep bowl of diplomat cream covered and refrigerated while you make the hazelnut feuilletine crunch.

DARK CHOCOLATE GANACHE

Ingredients:

125g heavy/double cream (I used a combination)

150g 54% dark chocolate couverture

15g unsalted butter, room temperature and softened

Pinches of salt

10g light corn syrup (optional)

Steps:

1. Heat dark chocolate using double boiling or microwave oven until slightly softened (not necessarily melted). Set aside.

2. Heat cream, corn syrup and salt in a saucepan until it just starts to bubble. Pour over chocolate and let it sit for a minute. Gently stir in one direction with spatula until chocolate is melted and smooth.

3. Add butter and stir until well mixed. Set aside to firm up at cool room temperature. 

You may prepare this a day in advance or while waiting for the Swiss roll to firm up in the freezer. I prefer to make this a day in advance to avoid having too many things to do on the day of baking and assembling the log cake. It is safe to store the ganache overnight at cool room temperature in airtight condition. Store the ganache in fridge if you need longer storage but it has to come to room temperature and have a toothpaste consistency before you can use it to coat the log cake.

CHOCOLATE HAZELNUT CHIFFON SPONGE 

This sponge is mild flavoured as the rest of the components are rich and strong flavoured. The hazelnut flour addition serves more to affect the texture rather than taste so you won't taste much of it, much like how a little almond flour is used to replace wheat flour in many cakes in traditional pastry making. Some hazelnut flour is generated in the process of getting finely chopped nuts out of the blender system so we might as well put it into good use!

Ingredients (makes two 10x12" sheet cakes):

Egg yolk batter

6 egg yolks (62-65g eggs with shells on)

20g Dutch processed cocoa powder *

64g boiling water

64g cake flour

1/4 tsp baking soda

16g hazelnut flour (replace with cake flour for regular cakes)

54 oil (I used canola)

1 tsp vanilla extract

1 tsp Kahlua coffee liqueur (may replace with vanilla)

Pinches of salt

Meringue**

6 egg whites

90g sugar***

1/2 tsp cream of tartar

* You may use regular cocoa powder. If so, increase baking soda to 1/2 tsp. Note that the chocolate flavour is mild for this cake as I did not want the chocolate (especially from the ganache) to overpower the hazelnut flavour. If you prefer it more chocolatey you may coat the sponge with a thin layer of dark chocolate ganache before layering on the hazelnut feuilletine crunch and diplomat cream.

** If your oven cannot fit two trays, divide the ingredients into two. Make the egg yolk batter for two trays worth but make the meringue for one tray portion only when you are about to bake it.

*** I used a combination of 10g caster sugar and 35g Allulose to make it a bit more diabetic friendly.

Steps:

1. Preheat oven to 165C fan/180C top and bottom heat only. Set oven rack to middle position. Line baking trays with parchment paper or Teflon sheet. 

2. Dissolve cocoa powder in boiling water to form a thin paste. Once cooled, add extract/coffee liqueur and salt. Mix well. Set aside.

3. Prepare egg yolk batter. Whisk egg yolks until pale and thick. Add oil and whisk until smooth. Add chocolate paste and whisk until combined. 

4. In a small bowl, sift cake flour and baking soda together with a fine sieve. Add hazelnut flour and whisk together. Sift flour mix into egg yolk batter using a coarse sieve and whisk until well combined. 

5. Make meringue. In a clean metal bowl, beat egg whites with cream of tartar until firm peaks or just reach stiff peaks, gradually adding in sugar once egg whites are foamy.

6. Quickly but gently fold meringue into egg yolk batter in three additions. Pour batter into prepared trays and smooth the batter using a bench scraper or spatula.

7. Bake for 12-14 min or until skewer comes out clean. Immediately flip the cake out onto fresh sheet of parchment paper/Teflon sheet and roll up to cool completely. You may use Teflon sheet if you prefer the sponge not to have wrinkle lines. The wrinkles won't be visible anyway because it is going to be covered by the ganache.

Prepare the hazelnut feuilletine crunch while waiting for the sponge to cool.

HAZELNUT FEUILLETINE CRUNCH

Ingredients:

75g double cream/heavy cream (I used a combination)

150g white chocolate couverture

150g hazelnut praline paste

60g feuilletine

60g finely chopped toasted hazelnuts

Steps:

Make sure you have the chocolate hazelnut sponge and hazelnut praline diplomat cream ready before you make the feuilletine crunch.

1. Melt white chocolate and cream over double boiler. Stir until smooth. Be careful not to overheat! Using a thick glass bowl over hot (not boiling) water helps to control the heat a little. Do not let the water touch the bottom of the bowl.

2. Warm up the hazelnut praline paste in microwave oven for 10 seconds at medium to medium-high powder. Add to melted chocolate. Stir until smooth.

3. Add feuilletine and chopped nuts. Stir until well mixed. If the mixture firms up too much at this point, reheat gently over double-boiler to spreadable consistency.

ASSEMBLY

Items to prepare:

6 x 9" cakeboards

Cake decorations/ornaments

Snow powder (optional)

Chocolate hazelnut chiffon sponges

Hazelnut feuilletine crunch

Hazelnut praline diplomat cream

Dark chocolate ganache

1. Unroll sponge. Spread a thin layer of dark chocolate ganache (optional and only if you prefer it more chocolatey. I didn't add this layer). Spread a thin layer of hazelnut feuilletine crunch, leaving about half an inch border around uncovered.

2. Spread a layer of hazelnut praline diplomat cream over the feuilletine crunch. Make sure the cream is thinner around the edges of the sponge.

3. Roll it up into a tight roll, using a bench scraper or long metal ruler to help you tighten the roll (see reel below). Freeze for 1 hour. You may prepare the dark chocolate ganache at this point if you haven't done so.

4. Remove Swiss roll from freezer and cut the ends off with a serrated knife. Reserve the cut-off pieces. 

5. Apply a small amount of ganache on a 6 x 9" cakeboard. I added a little diplomat cream as well but it's optional. Carefully place the Swiss roll on the cakeboard. Coat the Swiss roll surface with dark chocolate ganache using a small spatula.

6. Attach the cut-off pieces of Swiss roll onto the main roll cake and coat with ganache. Use the small spatula to make bark lines on the surface. You may use a fork if you wish, just like I did in the previous years.

7. Add any plastic cake ornaments, or in my case, snowman marshmallows as well. Finish off with a light dusting of snow powder if you wish. Store the cake in fridge for up to a week, in the freezer for longer storage. 

You may refer to this second reel to see the process of making the log cake out of the hazelnut items.

https://www.instagram.com/reel/CmY49RsArbF/?igshid=NTdlMDg3MTY=

Any leftover cream, ganache, praline and chopped nuts can be mixed together and frozen to make a delicious hazelnut praline chocolate ice-cream! But if you want this to happen, make sure you make double portion of diplomat cream! Add a little melted bloomed gelatin as well to keep it less icy in texture.

I made double portion of diplomat cream!

with lots of love,

Phay Shing