To make the Torta Caprese, start by placing the softened butter, half of the powdered sugar, and vanilla extract in the bowl of a stand mixer. Beat on medium-high speed for about 5 minutes, then add the pinch of salt and the egg yolks, also at room temperature.

In another bowl, combine the grated chocolate, almond flour, hazelnut flour, potato starch, baking powder, and cocoa powder.

Mix well and set aside.

Add one third of the whipped egg whites to the butter and yolk mixture, then add one third of the dry ingredients. Gently fold with a spatula, mixing from bottom to top. Continue alternating and folding in the rest of the egg whites and dry ingredients until you have a uniform batter.

Smooth the top and bake in a preheated static oven at 350°F (175°C) for about 45 minutes.

Let cool on a wire rack, then dust with powdered sugar before serving.