Line a cookie sheet with a silicone mat or parchment paper.
In a food processor add the powdered sugar and almond flour and pulse until fully combined and rid of lumps. Sift the dry ingredients into a large bowl. If you don’t have a food processor you can just sift the ingredients together.
In a medium bowl, prepare the french meringue. Beat the egg whites on low speed until they get frothy. Add one drop of food coloring at this point, if desired. Increase the speed and slowly add the sugar. Beat until stiff peaks form.
Add the french meringue into the dry ingredients and begin to gently fold with a silicone spatula. You will know the batter is ready when the ingredients are fully combined and not streaky. You should be able to hold the spatula above the bowl and draw a figure 8 smoothly without the batter breaking off.
Transfer the batter to a piping bag fitted with a piping tip. Pipe 1-inch disks onto the prepared cookie sheet.
Firmly tap the cookie sheet onto the counter 3 or 4 times to bring any air bubbles to the surface. Use a toothpick to pop any remaining air bubbles. If desired, sprinkle ground cinnamon over each macaron at this point.
Let the macarons rest for an hour. There needs to be a dry layer on the top. You should be able to run your finger over the top without any transferring to your finger.
Preheat the oven to 280 degrees (F).
Place the macarons on the middle rack of the oven and bake for 5 minutes, rotate the cookie sheet, bake for another 5 minutes, and rotate the cookie sheet again, bake for 5 minutes. 15 minutes in total.
Remove from the oven and allow to cool completely. They should peel off the mat easily.
When the macarons are cooled peel them off of the mat and match each shell to another that is the same size.