Chocolate Stump Cake with Meringue Mushrooms

I don't usually accept last minute requests but this one I couldn't refuse. My mum asked for a logcake I can make at my convenience, so I decided to let this request ride on a planned bake that involves making my ultimate chocolate cake. I usually bake chocolate chiffon sponge for log cakes as the sponge is soft and flexible enough to roll into swiss roll. Since the sponge I use for my ultimate chocolate cake isn't suitable for making swiss rolls, I make a stump cake instead 😊

Mushroom meringues as deco! 

I followed my original recipe closely, except that I tweaked the chocolate ganache to make a firmer one for the bark patterns, and I made chocolate whipped cream for the rings on the stump.

When I shared the photo of the mushroom meringues on social media, some were interested how I made them crisp and non sticky in humid Singapore. I will share the detailed recipe and tips in this blog post. I applied what I learnt from macaron making to create a meringue that remains crisp for a longer time.

Recipe for mushroom meringues
Ingredients (makes about 25 mushrooms) :
40g egg whites (about 1 large egg)
70g icing sugar (with cornflour added)
1 tsp cornflour
1/8 tsp fine salt
1/8 tsp cream of tartar
Cocoa powder (for dusting)

Notes
Traditional meringues are made using caster sugar insted of icing sugar. I chose to use icing sugar as it is much finer in texture and therefore more easily dissolved in the egg whites. Any undissolved sugar grains in the meringue will cause meringues to collapse a little during baking. Traditional recipes don't call for the addition of more cornflour but I recommend adding a little to help the baked cookies remain crisp and dry longer. Salt is optional but I included to balance the taste. Cream of tartar may be substituted with lemon juice if you prefer. The ratio of egg whites:sugar is traditionally about 1:2. I reduced it a little. Don't reduce by too much as it will affect the stability. Some people make swiss or italian meringues for better stability but what I am sharing here is the simplest method.

Steps:
1. In a small bowl, mix icing sugar, fine salt and cornflour. Set aside. Preheat oven to 100-110°C as read by the thermometer (no higher than that). Line baking tray with parchment paper.

2. In a clean metal bowl, beat egg whites with cream of tartar until foamy. Gradually add sugar mixture and beat at medium high speed until firm peaks form like below. This should take about 10 minutes.

3. Transfer meringue into piping bag fitted with a wilton #12 tip (about 8mm diameter). To pipe the mushroom caps, gently squeeze the bag with the tip placed 1cm away from baking tray surface until a mound forms. Release pressure and twirl the tip horizontally to try to release the tip from meringue without forming a peak. Dont worry if a peak forms. Just use a damp finger (not dripping wet) to tap down the peak gently. To pipe the mushroom stems, pipe a vertical column about 2cm tall by slowly moving the tip away from baking tray surface as you pipe. Tap down the peak gently with damp finger. You may pipe mushrooms of varying sizes for some variety.

4. Lightly dust the mushroom caps with a little sifted cocoa powder if you wish.

Piped and dusted with cocoa powder

5. Bake at middle rack without the fan on for 2 hours. Make sure the oven temperature doesn't exceed 110°C or the meringues may crack. If you don't mind a little cracking happening to make the mushrooms look a little more rustic, you may increase the temperature to 120°C. Open the oven every half an hour to release the steam build up in the oven. Traditional baking temperature is 90°C but I find that this may not dry the meringues out sufficiently and the surfaces may remain sticky.

To assemble the mushrooms, cool completely inside the oven. Dig a little hole at the base of the mushroom caps such that the stems can sit inside comfortably.  You may attach the caps onto the stems using melted chocolate or in my case, I used royal icing but dried the assembled mushrooms  in the oven for half an hour at 100°C.

Cute meringue mushrooms! 

Store the meringues in airtight container at room temperature.


You may refer to this post for the chocolate sponge and chocolate custard recipe. The portion is suitable for 7 to 8 inch sponge cake. I used only three-quarters of it as I used the rest of the batter for another bake. This stump cake that I made has three 6" sponge layers. The other bake I did concurrently had a small amount of homemade raspberry jam which I used to brush the sponge layers during assembly. This is optional but I used it since I have it. You may bake the cake layers in square pans if you dont have round ones and just cut to the desired shape and size using a clean cakeboard as your template. I actually baked the 3 sponge cakes in three 7x7" square trays, and then used a 6inch cakeboard as my template to cut to size.

Dark choc ganache (for bark) 
Ingredients:
150g bitter dark chocolate couverture 74%*
150g dark chocolate couverture 56%*
200g whipping cream

* you may use one type of couverture

Steps:
1. Place all ingredients in a heatproof bowl and set it over a pot of freshly boiled water without the water touching base of bowl. Let it sit for a few minutes. Use a spatula to stir the mixture until all the chocolate is melted and ganache is smooth.

2. Set aside to firm up at room temperature

Chocolate cake filling
Ingredients:
200g chocolate custard
150g dark chocolate ganache

Steps :
1. Portion out 150g of dark chocolate ganache above and chill it briefly in the freezer for 2 min. Use an electric mixer to whip the ganache until it is lightened in texture but smooth and creamy.

2. Fold the whipped ganache into the chocolate custard.

3. Transfer filling into piping bag fitted with a round piping tip of your choice.

Chocolate whipped cream (for rings on stump) 
50g whip topping (or double cream/ heavy cream)
40g dark chocolate ganache
10g chocolate custard

Steps:
1. Beat chilled whipping cream until firm peaks form. Be careful not to overwhip if you are using full dairy cream.

2. Fold in chocolate custard and chocolate ganache in a few additions until mixture is smooth.

3. Transfer into piping bag fitted with a wilton #12 tip (or any round piping tip of your choice)

Assembly
1. Apply a little ganache on cakeboard. Place first layer of sponge on top. Brush with syrup or jam if desired.

2. Apply a thin layer of custard with a spatula

3. Pipe the filling as shown below (3rd picture). Place the second sponge on top and press down gently. Repeat with the next layer.

4. Coat the top sponge with some chocolate whipped cream and use a spatula to smooth it out.

5. Coat the sides of the cake with dark chocolate ganache. Don't worry about being neat as you don't have to be!

6. Pipe rings of the stump on top using chocolate whipped cream. Use a fork to draw out the bark patterns by running the tines upwards.  Chill the cake in fridge until ready to serve. This chocolate cake tastes the best after 3 or 4 days of storage when the flavours have matured!

Unadorned cake! Still looks good! 

Decorate the cake with meringue mushrooms as you wish. You can add on other plastic christmas cake deco as well!

With love,
Phay Shing