At 225°F, place two oven racks evenly spaced from the top and bottom of the oven. On two pieces of parchment, trace three 8" circles. On two baking pans, flip the parchment over so the ink side is on the bottom.

Salt, cream of tartar, and egg whites should all be combined in the bowl of a stand mixer. Beat on medium speed until little bubbles start to form. Whip at medium-high speed until soft peaks begin to form. Add the sugar gradually while the mixer is running, then continue to whisk until the meringue is stiff and sparkly but not dry.

Combine the cocoa powder and nut flour in a small bowl. With a spatula, fold in the whites after sprinkling half of the mixture over the whipped egg whites. Fold the second half of the cocoa mixture in the same manner, stopping just before the colour becomes even and streak-free. The mixture ought to be thick and smooth.

Form batter discs inside the circles on the parchment using a little spatula or piping bag.

The discs should bake for an hour. After the oven has been turned off, allow the discs inside to dry for at least three hours or even overnight.

Put the caramel and 1/2 cup of the heavy cream in a medium heatproof bowl. Until the mixture is smooth, microwave the mixture in 20-second intervals while stirring. Add the remaining heavy cream and stir. Put the contents of the bowl of a stand mixer in the refrigerator for at least an hour.

Beat the ingredients until soft peaks form before assembling the cake. Beat the cream until it forms a medium peak after adding the salt and confectioners' sugar.

Combine all the ingredients in a mixing bowl and whip with a whisk attachment until frothy and creamy.

Pipe marble-sized spheres of the hazelnut filling onto one of the dacquoise discs, leaving some spaces between them for the whipped cream. Place the disc on a serving platter. The hazelnut filling should be covered with a third of the caramel whipped cream before the second disc is placed on top. The remaining hazelnut filling and a further third of the whipped cream should be piped. Place the final disc on top and cover with extra whipped cream. Add some chopped nuts on top.

Dacquoise leftovers should be stored in the refrigerator for up to two days to prevent the layers of meringue from becoming soggy.