Chocolate cake layers
- Wash the hazelnuts; toast them in the oven at 160C (320F) for about 10-15 min. After that, transfer the nuts to the food processor, and grind them into small pieces (do not crush to powder, however).
- Combine the eggs and sugar together, and whip the mixture until frothy and lightened. Add the sieved dry ingredients and carefully fold them in with a silicone spatula, trying to keep the mixture as airy as possible. Once that is done, add the chopped nuts, and mix it all together one more time.
- Evenly spraed the cake mixture between two 18cm (7.10 inch) baking pans, then bake it at 180C (356F) for about 30 min. Use a toothpick to check if the cakes are ready - it should come out completely dry. Leave the cakes to cool, then slice both of them into 2 layers with a cake leveler.
- To make the filling, melt the chocolate in the microwave or in a hot water bath, and then leave it to cool to room temperature.
- Whip the softened butter until you get a fluffy and light-colored mixture; then start gradually pouring in the melted chocolate (one spoon at a time), without stopping whipping. Avoid adding all the chocolate at once, otherwise the butter will melt - and we definitely don’t want that!
- Add the room temperatured Nutella. Take your waffles, and chop it into small pieces; then add the crumbs to the filling mixture. Mix it all together with a spatula.
Follow the next assembling order: sponge cake layer, ⅓ filling, sponge cake layer, ⅓ filling, sponge cake layer, ⅓ filling, sponge cake layer.
If you want, you can also decorate your cake with some chocolate ganache (chocolate + whipped cream in the 1:1 ratio) or glaze it (having refrigerated it beforehand) with some chocolate gourmet glaze (melt 100g (3.55 oz) of chocolate, then add 33g (1.20 oz) of vegetable oil and 33g (1.20 oz) of chopped nuts; let the mixture to cool, and glaze the cake with it).