Gluten free dark chocolate layer sponge cake

Ollie

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A rich birthday treat.

It wasn’t until 1879 that Robert Lindt developed a method for making smoother chocolate. Then, it became easier to bake with chocolate. And, it was in 1886 that American cooks began to add melted chocolate to cake batter to make the first chocolate cakes in the US.

The sponge cake is thought to be one of the first of the non-yeasted cakes made, and the first recipe was found in a book written in 1615. One variation of the sponge cake is the Italian génoise cake (which is the basis of a lot of Italian and French cuisine, also, this cake is free of any form of chemical leavening), another variation is the American chiffon cake (based on the ‘foaming’ method). The sponge part evolved from the classic butter or pound cake (‘batter’ method). It was the Victorian creation of baking powder that enabled the sponge mixture to rise higher than previously possible. And, to celebrate, a patriotic cake called the Victoria sponge was created (after Queen Victoria). The Victoria sponge has a layer of raspberry jam and vanilla cream ‘sandwiched’ between the layers of the vanilla sponge cake.

This particular cake is a chocolate sponge cake that has both a chocolate layer of filling and, a chocolate topping or frosting, and the sponge, itself, is in fact based on a modified form of a chocolate cupcake mixture. The chocolate layer sponge cake recipe is taken, with slight modifications, from America’s Test Kitchen’s gluten free testing and development programme. And, for once, here is a gluten free sponge cake that actually works and tastes just like a gluten version – fluffy, tender, moist, with a deep chocolate flavour, and that holds together well.

Ingredients (cake):
Grape seed oil 216g (1C)
Dark (72% min) chocolate (chopped) 150g
Cocoa powder (unsweetened) 60g
Gluten-free flour mix* 200g
Baking powder 1 1/2tsp
Bicarbonate of soda 1tsp
Gum Arabic (or Guar gum) 1tsp
Salt 1tsp
Eggs (large) 4
Vanilla extract 2tsp
Cane sugar 300g
Hemp milk 225g
Dark chocolate ‘ganache’ filling**
Dark chocolate ‘buttercream’ topping***

*Gluten-free flour mix:
White rice flour 680g
Brown rice flour 212g
Potato starch 198g
Tapioca flour/starch 85g
Total weight 1175g

Method (cake):
Preheat oven to 180C (note that sponge mixtures are particularly sensitive to cooking temperature and times – what follows is based on an electric fan oven that heats fairly accurately)

Grease two 9in (23cm) round sandwich/cake pans, lining both bottoms and sides with parchment paper and grease lightly.

(Bowl 1) In a bain-marie (double boiler) slowly and gently melt the chopped chocolate, combined with the grape seed oil and cocoa powder, stirring occasionally with a metal spoon, especially at the end when the heat is turned off and there are still some unmelted pieces of chocolate left, and stir until smooth. Set aside to cool slightly.

(Bowl 2) By hand, whisk together the GF flour mix, baking powder, bicarbonate of soda, gum Arabic (or guar gum), and salt; using a spoon, heap the flour mix from the side of the bowl into the centre and whisk; repeat three times.

(Bowl 3) In a large bowl, add three eggs (one at a time), whisk by hand with the vanilla essence; add 1Tbsp of flour mix and whisk until incorporated; add the final egg and whisk by hand; add and whisk cane sugar until it is just combined; add cooled chocolate mix and half of the hemp milk and whisk until combined; fold in flour mix a quarter at a time with a spoon, and finally add the rest of the hemp milk, until the sponge cake batter is thoroughly combined, scraping down the sides as required. (The mixing is done by hand, as it is detrimental to the sponge mix if air is beaten in too vigorously, over beaten (which it is easy to do with a stand mixer) resulting in a central ‘caving in’ of the top surface)

Divide sponge cake batter evenly between the two prepared pans and smooth the tops with an offset metal spatula.

Place filled pans in the middle of the oven and bake for 30 – 32mins (you may need to experiment with this with your own oven), keeping the door closed throughout the bake, until a skewer comes out clear when it is inserted into the middle of the sponge cake.

When the sponge cakes are ‘done’, switch off the oven, open the oven door, and let the sponge cakes ‘cool’ in the oven for 10mins (this will help stop any caving-in of the sponge top).
Remove sponge cakes from the oven and let them cool in their pans, placed on a wire rack, for a further 10mins.
Remove sponge cakes from their pans, discard the parchment paper and let them cool for 1 1/2hr.

Method (building up the chocolate layer sponge cake):
Use a cake stand, large platter, serving tray, or a square of cardboard covered with parchment paper, and line it with four strips of parchment paper to make the edges of an overlapping rectangle that goes beyond the side of the sponge cake.

Place one (layer of) sponge cake on a covered cake stand, large platter, serving tray, or covered square of cardboard. This is so that you can turn the cake around as required.

Take out the dark chocolate ‘ganache’ filling, and if required, gently loosen the mixture with a spatula; spread ganache evenly over the top of the first layer; and then place the second layer of sponge cake on top of this ganache and gently press down to ‘seal’, if any ganache escapes to the side spread it around the side with a spatula.

Take out the dark chocolate ‘buttercream’ topping, and if required, gently ‘loosen’ the mixture with a spatula; divide into two (40% for the top and 60% for the cake side).

Spread the buttercream evenly over the top of the sponge cake, going right up to the side of the cake, again using a gentle motion with an offset metal spatula.
Spread the rest of the buttercream evenly around the side of the cake, right up to the top surface of the topping, and merge. Avoid pressing too hard, or the layer will become thin.

For a rustic surface finish, leave it as it is, as the spatula spreads the buttercream, or rough it up with a fork. Gently remove the four strips of overlapping parchment paper.
For a smooth finish, wet (so that there is minimal pickup of buttercream) an offset metal spatula and smooth the buttercream until it is flat and smooth. Wiping the spatula clean, as required, and rewetting. Gently remove the four strips of overlapping parchment paper from under the sponge cake.

Place the chocolate layer sponge cake in a refrigerator until it is time to eat (this firms up the buttercream) or serve straight away. Preferably eat the same day.

Enjoy!!!

**Dark chocolate ‘ganache’ filling
Ingredients:

Dark (72% min) chocolate (chopped) 265g
Butter (softened) 45g
Honey (clear) 20g (1Tbsp)
Vanilla extract 1 3/4tsp
Heavy cream 245g
Salt 1/8tsp

Method:
In a bain-marie (double boiler) slowly and gently melt chopped chocolate, using a spoon to occasionally mix, especially for the last pieces when the heat is removed; set aside to cool.

In a large bowl, and using a handheld mixer with two beaters, beat softened butter, heavy cream, vanilla essence and salt, at medium speed for 1 - 3mins, until all are incorporated.
Add cooled, melted chocolate and honey, mix at a low speed until smooth – 2mins.
Beat at medium-high speed for 5 - 8mins until mixture is light and fluffy.

Place ‘ganache’ filling in a refrigerator for 15-30mins if required, to stiffen up the mix, not too much or it will be difficult to spread.

***Dark chocolate ‘buttercream’ topping
Ingredients:

Dark (72% min) chocolate (chopped) 500g
Butter (softened) 425g
Cane sugar (powdered) 360g
Cocoa powder (unsweetened) 4 1/4Tbsp
Vanilla extract 2tsp
Salt 1/8tsp

Method:
Melt chopped chocolate in a bain-marie (double boiler) slowly and gently, using a spoon to encourage the final pieces to melt; add salt and vanilla essence and stir until salt dissolves.

Place cane sugar granules in a coffee grinder and grind granules to a fine powder.

In a separate large bowl beat the butter with a handheld mixer for 36 – 60sec at a medium-high speed until smooth; reduce speed to medium-low and slowly add powdered cane sugar and cocoa powder; beat until smooth, 2 – 5mins.
Beat in chocolate mix, and increase speed to medium-high, until the mixture is light and fluffy, between 5 – 8mins.

Divide up ‘buttercream’ in the proportions of 40% (for the top) and 60% (for the sides) and place in two bowls.

Place ‘buttercream’ in a refrigerator for 15 - 30mins to firm up, only if it is too ‘runny’ to stick to the side of the cake without it running loosely down the side.

Enjoy!!! (Sorry, no picture it was eaten too quickly!)
 
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