Line a baking sheet with parchment paper, draw two 7 inch (18 cm) diameter circles, invert the parchment paper and set aside until ready to use. Have a pastry bag with a plain tip (about ½ inch, 1 cm) ready and preheat oven to 300F (150C).
Using a food processor grind together the powdered sugar with almond powder and cocoa powder, to obtain a fine powder. Sift through a sieve into a large bowl.
Pour 55g egg whites over the sieved almonds.
Place the other 55g egg whites and salt into a mixing bowl. Set aside until you prepare the sugar syrup.
In a small saucepan combine granulated sugar with water and place on medium heat. Using a candy thermometer measure syrup temperature. When it reaches 230 F (112C) start whipping the egg whites. When the syrup reaches 244F (118C) pour it over the whipped egg whites while mixing continuously. Continue beating until the bowl has cooled slightly, and glossy stiff peaks have formed.
Add the whipped whites over the almond mixture and using a rubber or silicone spatula gently fold in until combined and smooth. Work the batter until it flows in very thick ribbons when the spatula is lifted.
Transfer the mixture to the piping bag fitted with a 1/2 inch (1 cm) plain tip.
Following the drawn circles, pipe disks of batter in a spiral.
Rap the baking sheet a few times firmly on the counter top to flatten the macaron disks and to remove air bubbles.
Bake for about 20 minutes. Let cool before removing from baking sheet.
Use the remaining batter to make regular macarons.