Line a clean, flat cookie sheet with a Silpat or parchment paper, and set it aside.
Preheat oven to 325 degrees and place rack in middle of oven.
Sift together almond flour (or ground up almond meal like I did), cocoa powder, and confectioners' sugar and set aside. Make sure the mixture is well-sifted!
In a spotlessly clean stand mixer bowl, whip the aged, room temperature egg whites on medium speed until they are foamy and you can start to see the tines of the whip leaving a trail in the whites, about 1 to 2 minutes.
Add 1 tablespoon of sugar, and continue to whip for about 30 to 45 seconds. Add another tablespoon of sugar, and whip again for another 30 to 45 seconds. Repeat with the third and fourth tablespoons of sugar.
When all of the sugar is mixed in, whip the whites for about another minute or two until they become glossy and shiny. Remove from mixer.
Fold in about half of the almond flour/confectioners' sugar mix; when most of it is folded in, add the rest of the dry mix. Fold until mixture is smooth and a little stiff -- it should drop smoothly off of the spatula.
Using a piping bag and a small round tip, pipe out small rounds of macaron batter about 1 inch in diameter. Try to pipe straight down and quickly pull away when you are done to minimize peaks. Pipe until you’ve used up all the batter.
Rap the cookie sheet several times to flatten out the mounds and to pop any bubbles that might be in the batter.
Let cookies rest for about 15 to 30 minutes, until they are no longer tacky to the touch.
Place in oven, and immediately turn oven down to 300 degrees. After 8 minutes, rotate the cookie sheet. Depending upon your oven, cookies take from 15 to 20 minutes (mine took 15 minutes). Remove from oven, and let cool.
Remove the meringues from the parchment and pair them by size.