Melt the butter over a bain-marie. Sift the flour and cocoa powder together. Line the cake tin with baking parchment.
Make the meringue. Add 1/2 of the granulated sugar in 3 batches to the egg whites. Beat at a high speed with your hand mixer. After some time lower the speed and continue to beat for another 2 minutes to make the texture smooth.
In a separate bowl add the egg yolks and the rest of the sugar. Beat at a high speed with your hand mixer until pale and fluffy, and leaves a trail when the mixer is lifted.
Add a little of meringue into the egg yolk mixture and transfer the mixture back into the meringue bowl. When it is 70% combined, add the flour and cocoa powder. Also add the melted butter at this point.
Pour the batter into the prepared cake tin and flatten the surface with a scraper. Drop the tin several times from a height to get rid of large air bubbles. Bake at 190C for 12 to 15 minutes.
Remove the sponge from the tin when it is done. Cover with a cloth to prevent it drying out and leave to cool.
Make the cream. Whisk the cream until a thin ribbon forms when a whisk is lifted. Add 1/2 of the frozen raspberries. Continue to whisk until soft peak stage, and then add the rest of the raspberries. Continue to whisk until stiff peaks form.
After cooling, slice the top and bottom ends of the cake off. Slice the near-side end straight and the far-side diagonally.
Place the sponge onto baking parchment and put more of the filling cream on the near-side. Spread the cream, leaving a thin border on the far-side.
Start to roll up the cake tightly from the near-side, and then use the baking parchment to roll the rest of the cake.
When you finish rolling, gently squeeze to set it in place, and place joint-side down. Twist the excess baking parchment at both sides to secure the cake and put it in the fridge to set.
Slice off both ends and slice into your desired thickness. And it's done ♪
Serve onto a plate and enjoy.
Story Behind this Recipe
I like the combination of chocolate and raspberries. I decided to match them in a roll cake.
It is easier to slice the cake after the filling cream has set completely. By adding the raspberries to the cream in two batches, you can still enjoy some chunks of raspberries. It's also OK if you want to add them in one go.