Chocolate Banana Cake

One of my favourite flavour combinations of all time.

I didn’t have any ripe bananas so I cheated and baked some to concentrate the flavour a little bit.

The baked bananas go into the banana curd which goes in between each layer of Devil’s food chocolate cake, as well as fresh bananas for some structural support. This combined with an intensely chocolatey buttercream made from some very expensive Valrhona Guanaja chocolate just really adds flavour to the cake.

I decided to decorate with some stereotypical drips (which reminded me of this kind of monk hairstyle) and dried banana slices lining the top of the cake.

Overall I really liked the cake! I thought the banana curd loses its banana flavour over time for some reason though, so I would recommend eating this within the day after making in order to maximise banana flavour.

I got the cake recipe from here, the chocolate buttercream recipe from here, and the banana curd recipe from here (although I really cut down on the sugar there).

Ingredients (makes a 3-layered 6 inch cake)

Devil’s Food Cake

• 170g unsalted butter
• 170g coffee
• 43g Dutch-process cocoa powder
• 85g dark chocolate, about 72%
• 227g brown sugar
• 8g vanilla
• 2g salt
• 3 large eggs, from fridge
• 1.5 large egg yolks, from fridge (for 1/2 a egg yolk just weigh out an egg yolk and add 1/2 the weight of the weighed yolk)
• 128g all-purpose flour
• 7g baking soda

Banana curd

• 2 eggs, room temp
• 2 tbsp butter, room temp
• 1 tbsp lemon juice
• 80g sugar
• 2 ripe bananas

Chocolate buttercream

• ¼ cup heavy cream (58g)
• 58g chopped dark chocolate (around 70% chocolate)
• 170g unsalted butter, softened to around 18°C
• 127g powdered sugar
• 43g high-fat Dutch cocoa powder (I used Droste)
• 1 tsp vanilla
• 2g salt
• 3/8 instant espresso powder

Assembly

• Dried banana chips
• Fresh banana slices (about 1 banana worth)
• Chocolate ganache (84g dark chocolate, 1/4 cup whipping cream)

Method

Devil’s Food Cake

1. Adjust oven rack to lower-middle position and preheat oven to 350°F/180°C. Lightly grease your 6″ baking tins and line the bottom of the tin with a round of parchment paper.
2. In a saucepan, combine butter and coffee over low heat until butter is melted.
3. When melted, remove from heat and add in cocoa powder and chocolate.
4. Add in brown sugar, vanilla, and salt.
5. Mix in eggs and yolks, then sift in flour and baking soda.
6. Whisk to combine.
7. Pour batter into your lined baking tins.
8. Bake in preheated oven. Ideally you’d split your mixture into 3 lined baking tins and bake them together but if your kitchen is scuffed like me and you only have one pan, I baked 2/3 of the batter first followed by the remaining 1/3. The 2/3 batter took about 35 mins to bake and the remaining 1/3 batter took about 20 mins. Basically bake until cakes are firm but your finger can still leave an impression in the puffy crust, and a toothpick inserted in the center should come out clean with a few crumbs attached.
9. Cook cakes in the pan for an hour, then run a butter knife around the edges to loosen. Invert onto a wire rack, remove the parchment, and return cakes right side up.
10. When cakes are completely cooled, cut and level the cake.

Banana curd

1. (optional) If you don’t have any ripe bananas, try baking them first. Poke the bananas through the skin with a fork a couple of times, and bake the bananas in a preheated 220°C oven for 15 mins, or until bananas turn black and the flesh is tender. Remove the banana flesh from the skin, and let the flesh drain and cool in a colander to get rid of as much liquid as possible.
2. In a blender or food processor, add eggs, butter, lemon juice, sugar and then bananas (in that order).
3. Turn blender on high and blend until fully combined and silky smooth. If using food processor, start on low and then switch to high to achieve an extremely smooth consistency.
4. Pour all ingredients into a medium sauce pan over medium-low heat. Stir constantly for about 5-10 minutes or until mixture thickens and coats the back of your spoon. (you could try returning the drained banana liquid if you had baked your bananas to the mixture for extra banana flavour but you’d have to cook the mixture down further for the right consistency)
5. Remove from heat and allow to cool completely. (Can refrigerate for 2-3 hours to expedite)
6. Store banana curd in an airtight container in the refrigerator.

Chocolate buttercream

1. In a saucepan, bring the cream to a simmer. Meanwhile transfer chopped chocolate to a bowl.
2. Pour the cream onto the chopped chocolate, leave for a minute, then stir until smooth. Transfer the ganache to a shallow container and cool down to approximately 75°F (24°C), about 30 minutes.
3. In a large bowl, beat together butter, sifted powdered sugar, and sifted cocoa powder until dry ingredients are incorporated.
4. Add vanilla, salt, and espresso powder, and continue beating until frosting is creamy and smooth.
5. Add the cooled ganache, and continue beating until frosting is homogeneous. If you want a darker denser frosting you can stop here, and if you want a lighter paler frosting (with a higher yield) you can keep on beating the frosting.
6. Use buttercream straight away, or it can also be refrigerated in an airtight container for up to 2 weeks or frozen for several months. Bring buttercream to approximately 72°F (22°C) and re-whip before use.

Assembly

1. Pipe a ring of chocolate frosting around the perimeter of a cake layer (to form like a moat to stop the banana from leaking out).
2. Put a couple of tablespoons of banana curd in the middle, and add some cut fresh banana slices.
3. Pipe a bit more chocolate frosting over the top, level it roughly, and place the next cake layer.
4. Repeat steps 1-3.
5. Cover the whole cake with a thin layer of chocolate frosting (crumb coat), then refrigerate for 30 minutes. Then cover the whole cake again with chocolate frosting as smoothly as you can.
6. Refrigerate the cake. Meanwhile, prepare the chocolate ganache for the drips.
   • To make chocolate ganache, microwave 1/4 cup cream until it starts to steam and small bubbles just start to form. Meanwhile, add 84g chopped dark chocolate to a bowl.
   • When cream has finished heating, pour the cream over the chocolate and let sit for a minute, then stir until smooth. Don’t stir too vigorously or you’ll add bubbles to the ganache.
   • Allow ganache to cool until desired flow-iness, maybe about 10 minutes. Transfer to piping bag.
7. Decorate the cake with chocolate ganache, by piping the chocolate ganache around the perimeter of the top of the cake and allowing it to drip. Cover the top of the cake with chocolate ganache as well. Finish with dried bananas.

Notes

• Let the cake come to room temperature before serving (it just tastes better).
• The banana curd loses flavour over time for some reason, so don’t make it too far in advance.
• Use your favourite dark chocolate for the frosting, the frosting is only as good as the chocolate you use.