To make basic macarons, start with 2/3 cup sliced blanched almonds, and grind them in a food processor for 1 minute so they become a fine flour. Add 1 cup confectioners' sugar to the almond flour, and blend in the food processor for an additional minute. Use a metal sieve to remove any almond lumps from the mixture. Regrind those nuts in the food processor.
Whisk together 2 large egg whites that are at room temperature with 1/4 cup white granulated sugar until combined. Using an electric mixer, whisk the egg white mixture for 2 minutes at medium speed, 2 minutes at medium-high speed and 2 minutes on high speed. Peaks should form in the egg mixture.
Add food coloring to the egg whites if desired. Whisk for an additional 30 seconds on high in the electric mixer. Fold in dry ingredients with a spatula, but do not over-mix.
Using a pastry bag, pipe the macaron batter onto parchment paper-covered baking sheets so it forms approximately 40 to 50 3/4-inch rounds. Space rounds approximately 1 inch apart.
Bake the macarons in an oven preheated to 350 degrees Fahrenheit. Place the macarons onto a rack located on the lower third of the oven, and bake one sheet of macarons at a time. Bake for approximately 13 minutes, and rotate the baking sheet once during that time to ensure even baking.
Allow the macarons to cool completely. Sandwich two cookies together using jam or another filling. Wrap in plastic wrap, and refrigerate to keep the cookies fresh.