This Hazelnut Layer Cake, or Torta od lješnjaka in Croatian, is a classic. In my family, this has been the traditional birthday cake. The recipe comes from my aunt's Croatian cookbook from the 1950s.
The cake consists of layers of hazelnut sponge and a hazelnut frosting, which is cooked in a saucepan before being beaten until light and fluffy. It is flavorsome, nutty, and delicious! I hope you enjoy it as much as we do.
Toasted hazelnuts, toasted hazelnut flour or chocolate shavings, for decoration
Preheat the oven to 175C (350F).
Line a baking sheet with parchment paper and set aside. Butter a 23cm / 9in springform pan, place a parchment circle on the bottom, butter the parchment and set the pan aside.
Measure the ingredients.
Toast the hazelnut flour (or meal) for 5-7 minutes until fragrant, stirring the flour half way through to ensure even toasting. Toasting the flour will deepen its flavor, making it more nutty and complex. Let the flour cool completely before using.
Place the chocolate in a heatproof bowl and melt over a bain-marie or pot of simmering water. Stir until smooth and then set aside to cool.
In a clean bowl, beat the egg yolks until pale and light. Stir in coffee, salt, rum and melted chocolate until incorporated. Set aside.
In a separate and clean bowl, combine egg whites with cream of tartar and whip until the beginning of the soft peak stage. Slowly add the sugar, 1 tablespoon at a time. Whip well after each addition, gradually increasing the speed, until firm peaks.
Fold a third of the egg white mixture into yolk-chocolate mixture to lighten the batter. Continue to fold the remaining egg whites along with the hazelnut flour until incorporated. There should not be any egg white streaks in the batter but be careful not to overfold and deflate the whipped egg whites.
Immediately and gently pour the mixture into the prepared cake pan. Gently even out the top and put the pan on a baking sheet and then into the oven.
Bake for 30-40 minutes or until a skewer inserted in the center comes out clean and the top is golden.
Thoroughly cool the cake before unmolding it. It will deflate as it cools.
Make the hazelnut frosting as per the recipe.
When ready to assemble, invert the cake onto a cutting board, peel off parchment circle, and slice the cake horizontally into two layers using a long, serrated bread knife.
To decorate, place a cake layer on a serving plate – the top of the cake should now be the bottom. To keep the serving plate clean while frosting the cake, tuck 4 thin strips of parchment paper under the edges of the cake (or alternatively use a cake cardboard base and a cake decorating turntable). With a spatula or spoon, dollop a generous amount of frosting onto the top of the cake. Use an offset spatula to create a thick, even layer of frosting. Place the second layer on top. Generously apply frosting to the top and sides of the cake. Use an offset spatula to even out the top and sides, forming an even layer of frosting. Pipe frosting and/or place whole toasted hazelnuts, toasted hazelnut flour or chocolate shavings on the top/sides of the cake as decoration [I used toasted hazelnut flour on the sides and 3 toasted hazelnuts on the top of the cake]. Pull the parchment strips off after you have decorated the cake.
Allow the frosting to set in the refrigerator (at least 1 hour) before serving.
Store leftovers well wrapped or in an airtight container in the refrigerator for up to 3 days. When ready to serve again, take the cake out of the refrigerator at least 30 minutes before, so that it reaches room temperature.