Hazelnut Recipe

Prepare and bake sponge

Preheat oven to 350°F (175°C). Line a 9-inch (23 cm) round cake pan or prepare a sheet pan for a thinner sponge. Whisk together flour, cocoa powder, baking powder, and salt in a bowl and set aside. In a separate large bowl, whisk eggs and granulated sugar until pale and slightly thick (about 3–4 minutes by hand or 2 minutes with a mixer). Whisk in vegetable oil, milk, and vanilla. Gently fold dry ingredients into wet mixture until just combined, taking care not to deflate the batter. Pour into prepared pan and smooth the top. Bake 12–18 minutes for a sheet sponge or 20–25 minutes for a 9-inch pan, until a toothpick inserted in the center comes out clean. Cool in pan 10 minutes, then transfer to a rack to cool completely. Once cooled, slice horizontally into 2 even layers (or into layers appropriate to your serving size).

Bloom gelatin (if using)

If using gelatin for stability: sprinkle gelatin over 1 tablespoon cold water and let sit 5 minutes. Warm gently (microwave 5–8 seconds) until dissolved; do not boil. Let cool slightly.

Whip fresh cream

Chill mixing bowl and whisk. Pour chilled heavy cream into the bowl, add powdered sugar and vanilla. Whip on medium-high until soft peaks form. If using gelatin, while whipping slowly stream in the dissolved gelatin and continue to whip to medium peaks. Keep refrigerated until assembly.

Prepare chocolate cream

Whisk together powdered sugar and cocoa to remove lumps. In a chilled bowl, whip the chilled heavy cream to soft peaks. Fold in the sifted cocoa/powdered sugar mixture and the cooled melted dark chocolate until evenly combined and medium-firm peaks form. Refrigerate until needed.

Make gianduja

Place toasted hazelnuts in a food processor and pulse until crumbly, then continue processing until they release oil and form a paste (about 5–8 minutes). Add powdered sugar, melted chocolate, neutral oil, and salt; process until smooth and spreadable. If mixture is very thick, warm briefly or add an extra 1/4 tsp oil to loosen. Transfer to a bowl and cool to room temperature before assembly.

Make crunchy topping

In a small skillet over medium heat, melt sugar until it caramelizes to a light amber color. Stir in butter, then quickly add coarsely crushed roasted hazelnuts and stir to coat. Spread on a parchment-lined tray and let cool. Break into small pieces. Reserve until assembly.

Prepare ganache

Place chopped dark chocolate in a heatproof bowl. Pour the hot cream over the chocolate and let sit 2 minutes, then whisk until smooth and glossy. Stir in hazelnut paste or liqueur and butter if using. Let the ganache cool and thicken slightly until pourable but not too runny (about 10–15 minutes).

Assemble cake

Place one sponge layer on a serving plate or cake board. Spread a thin layer (~2–3 tbs) of the gianduja over the sponge; smooth. Pipe or spread about half of the fresh cream over the gianduja layer. Place the second sponge layer on top and press lightly. Spread the chocolate flavoured cream evenly over the top and sides (use remaining fresh cream for the sides if desired for contrast). Sprinkle the hazelnut crunch pieces between layers or on top where desired so there is a crunchy layer. Chill the assembled cake 15–20 minutes to set slightly.

Finish with ganache and garnish

Place the cake on a rack over a tray. Pour the cooled pourable ganache over the top, allowing it to drip down the sides; use a spatula to smooth if needed. Return cake to refrigerator for 20–30 minutes to set the ganache. Garnish with halved toasted hazelnuts around the edge and a light dusting of cocoa powder if desired. Let the cake rest at cool room temperature 10–15 minutes before slicing for cleaner cuts.