Line two baking sheets with parchment paper and have a pastry bag with a plain tip (about ½ inch, 1 cm) ready. Preheat oven to 285-300F (140-150C).
Using a food processor, grind the powdered sugar and almond powder together until fine. Sift through a sieve into a large bowl.
Place 55 g egg whites and white food coloring in a small bowl. Beat until well combined, then pour over the sifted 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 egg whites to the almond mixture and gently fold in using a rubber or silicone spatula until combined and smooth. Continue working the batter until it flows in thick ribbons when the spatula is lifted.
Transfer the mixture to the piping bag fitted with a 1/2 inch (1cm) plain tip.
Pipe the batter on the parchment-lined baking sheets in 1-inch (2.5 cm) circles, evenly spaced 1-inch (2cm) apart.
Rap the baking sheet firmly on the countertop a few times to flatten the macarons and remove any air bubbles.
Bake for 20-24 minutes. Let cool slightly before removing from the baking sheet.