Take the eggs out of the fridge and let them warm up to room temperature;
Preheat your oven to 250°F (121°C) and chop the hazelnuts into medium-coarse grains and have them ready to add to your meringue mixture. Pulse them intermittently in your food processor so the blade doesn’t heat up the nuts too much and render them bitter. I’d even suggest refrigerating your food processor bowl and blade before processing the nuts;
Separate your eggs, but be careful not to get yolks in the whites. Even a tiny bit of yolk can ruin the meringue. With the whisk attachment, beat the whites for 5-6 minutes until you get very stiff peaks. It should be fluffy, white, and thick;
Sift in the powdered sugar and the cocoa powder but add only a tablespoon at a time. Eventually, add the vanilla extract. (if you use a vanilla bean, split it down its length and scrape out the seeds from half a bean);
Beat on medium speed with the wire whip attachment until you have very stiff shiny peaks; it usually takes 2-3 minutes after adding the sugar. If the tip of the egg whites can stand straight up, the mixture is ready. Don’t over beat your batter either. Once you get stiff peaks, stop.
Fold in the hazelnuts and almonds with an upward movement in order to not deflate the meringue;
Put the mixture in a heat proof bowl over boiling water. Stir every few minutes or so for about 15 minutes or until it sets;
Remove it from the heat and shape the cookies. Use mini-paper cups and put a dollop of dough into each paper cup. Use two teaspoons because the dough is quite sticky;
Bake on parchment-lined trays at 250°F (121°C) on the medium-high rack (they must get dry but not burn) for about 35 minutes;
Then decrease the temperature to 200°F (100°C) and change to a convention oven (if your oven has this function) and let them dry for about 20 minutes with the oven door half-closed. The cookies must be light and very dry;
Take the cookies out of the oven and let them cool down completely. Close your eyes and take your first bite. So what is your initial impression?