Preheat oven to 285 for steel pans, or 300 for aluminum pans. Preheat for at least 10 minutes.
Measure out your granulated sugar in a small bowl; set aside.
Measure powdered sugar and almond flour together, then use a sifter to combine. This will make them smooth and lump-free. Set aside.
Place your bowl on the surface of your food scale. Hit "tare" button to zero out the weight of the bowl. Now measure the room temperature egg whites into the bowl of your KitchenAid stand mixer.
Add the clear vanilla extract.
Place bowl on mixer stand (this recipe is for the KitchenAid mixer), and attach the wire whisk beater. Set timer for one minute. Turn mixer to Speed 4, and slowly add sugar to egg whites, shaking it in a little at a time during that first minute.
When timer goes off, set mixer to Speed 6, and set timer for 2 minutes.
When timer goes off, set mixer to Speed 8, and set timer for 1 and 1/2 minutes (90 seconds). Coloring may be added just before this last mixing. Egg whites should look silky, yet stiff enough to hold the peak.
Now we'll make the macaronage: blend in dry ingredients, by moving a flexible spatula around the bowl, then cutting down through the middle, making sure to scrape the bottom for the flour and incorporate it into the meringue. You know you are done when the batter rolls off the spatula in a continuous ribbon. Batter will be thick...but can flow like a ribbon.
BAKER'S NOTE: I have several videos of making macaronage in my Instagram Highlights.
Insert Wilton #12 tip into the small opening of your piping bag. Scoop the macaronage into the bag, filling only half-way full, leaving room to twist the top closed in order to keep the batter from spilling out the top. Pipe the macrons by applying pressure until the batter flows out and just reaches the inner rim of the marked circle on your mat. Immediately release pressure and swirl tip to incorporate point back into the center of the cookie. See my tips on Instagram Highlights.
NOTE: if you will be using parchment paper -- search for online -- then download a template of circles and place underneath your parchment paper. You'll remove this before baking.
Once the full pan is piped, gently (or aggressively--no judgement here) bang the pan down onto the counter to release air bubbles. I usually place a towel on the counter before banging the pan. Use your scribe or toothpick to pop any large bubbles, in order to create smooth shells.
PREP FOR BAKING, METHOD ONE: Place your parchment paper or Silpat mat on the bottom of an upside-down baker's half sheet. Pipe your circles. Let rest about 5 minutes, bang (see above) then place them to bake in a pre-heated oven.
PREP FOR BAKING, METHOD TWO: Place your parchment paper or Silpat mat on the inside of a baker's half sheet (like normal). Pipe your circles. Let rest until your finger can glide across the top of the mac without stickiness, often up to 30 minutes. Bang (see above), then place them to bake in a pre-heated oven.
Bake for 20 minutes.
Once out of the oven, DO NOT -- I repeat -- do not remove from pan until they are completely cooled.
This recipe yields 36-42 completed cookies (about 72-84 shells).