Preheat the oven to 390°F (200°C) and prepare a non-spill baking sheet (no need to grease it). Or use a silicone baking mat or a 12 x 16 inches (30 x 40 cm) baking sheet lined with parchment paper. Grease the baking tray, then add the parchment paper and lightly grease it.

To make the cake batter, with a hand whisk, mix ground almonds, all-purpose flour, and icing sugar in a mixing bowl.

Melt butter in the microwave at 20-second intervals and let it cool.

Place whole eggs in the bowl of a stand mixer with a whisk attachment and whip for a few seconds.

Add the dry ingredients to the egg mixture and mix at medium speed for 3 minutes until creamy and homogeneous. Pour the cooled melted butter and gently mix with a rubber spatula.

In a separate clean bowl, whip egg whites at high speed with an electric hand mixer. Once foamy, gradually add caster sugar and beat until stiff peaks.

Gently fold the beaten egg whites into the almond preparation in two or three batches and carefully mix with a spatula.

Pour batter onto the prepared cake pan, smooth the surface with a long offset spatula, and bake for 10-15 minutes. If baking a silicone mold, place it on the oven rack. The sponge should be slightly golden and spring back with touching.

Remove the cake from the oven. Turn it onto a kitchen or tea towel generously sprinkled with icing sugar. Gently peel the baking mat or top layer of parchment paper (it was bottom during baking).

Sprinkle the sponge with icing sugar, roll the cake into the towel, and let it rest for 10 minutes. Then, unroll it and let it cool to room temperature.

To make the coffee mascarpone cream, place the prepared mascarpone (see the notes) in the bowl of a stand mixer fitted with a whisk attachment. Whip the cheese for a few seconds.

Add cold heavy cream, icing sugar, espresso coffee, and instant coffee powder to the bowl. Mix with a hand whisk to homogenize everything. Then, whisk with the stand mixer until medium peaks.  

To roll the cake, spread 2/3 of the cream filling in an even layer and smooth the surface with a bent spatula. Sprinkle with the chopped roasted hazelnuts.

Roll the biscuit from the short end, using the kitchen towel to help. Make sure the end of the roll is facing down. Tight roll as much as possible. Refrigerate it, still in the towel, for 4 hours. Wrap the bowl with the remaining cream with plastic film and refrigerate.

To decorate the cake, with a sharp knife, cut the ends of the cake for a neat appearance. Spread the remaining coffee cream over the top of the cake. Decorate it in the way you desire.