1. Preheat the oven to 350°F (180°C) and line a square 9×9 inches / 23x23cm (or similar rectangle dimensions) baking pan. Set aside.

 

2. Working with just one large bowl add the flour, erythritol, cocoa powder, baking powder, baking soda, and salt to the bowl and mix until well combined. Add the eggs, vanilla extract, oil, and milk and mix until combined. Add the hot water and espresso and mix everything until well combined. Pour the batter into the prepared baking tin and bake for 30-35 minutes or until a wooden skewer inserted into the center comes out clean. Take out of the oven and let cool for some time in the baking tin, then remove and let cool down completely on a wire rack.

 

3. For the ganache chop the chocolate coarsely and add together with the heavy cream and liquor to a heatproof bowl. Melt over a pot with simmering water or in the microwave. Stir until you get a nice and smooth ganache. Let cool down until thickened but not hard. Fill into a piping bag before you have to use it.

 

4. For the berry filling wash and dry the berries. If you use frozen ones, let them defrost. Try to save all the juices. Add the sugar and cornstarch to a small bowl and mix. Add water, lemon juice, and vanilla extract to a pot and mix. Add the cornstarch-sugar mixture and whisk until there are no more lumps. Bring the mixture to a boil, then add the berries and let simmer for 2-4 minutes – the berries should be soft but not mushy and the liquids should have thickened. Take off the heat and let cool down completely.

 

5. For the buttercream add the egg whites and sugar to a large heatproof bowl and place on a pot with simmering water. Mix slowly until the temperature of the mixture reaches a temperature of 160°F (71°C) and the sugar has dissolved completely. Take off the heat and mix with a kitchen machine or handheld mixer for about 5 minutes on high speed until the egg whites are glossy and stiff peaks form. The bowl should have room temperature. Add the soft butter in small pieces – one after another and mix in well each time. Add the vanilla extract and confectioners‘ sugar and mix first slowly, then on high speed for about 5 minutes until thick and creamy. Divide the buttercream into several portions and mix with the food colors you like. Fill into piping bags with different piping tips – keep some buttercream uncolored in the bowl.

 

6. To assemble the cake cut the cake in half and place the bottom part in the baking tin again. Pipe the ganache along the edge of the cake to create a barrier. Add the berries filling on top and distribute evenly up to the ganache barrier. Place the top cake half on top and press down a bit. Spread some of the white buttercream you kept in the bowl on top of the cake to cover it completely with a thin layer. Use the colored buttercream to pipe roses, swirls, and dots onto the cake. Sprinkle with some sugar sprinkles. Store in the fridge and let get back to room temperature before serving.