Blend the almond flour and powdered sugar without heating the mixture. Sift the resulting "tant pour tant" onto a sheet of parchment paper or into a bowl, then weigh the amount needed for the recipe.
Beat the egg whites on low speed in the bowl of the stand mixer fitted with the whisk attachment. As soon as they start to foam, add half of the sugar.
Continue beating until stiff peaks form, then add the remaining sugar. Beat further until you achieve a firm, shiny meringue with a bird's beak (the meringue forms a curved point at the end of the whisk).
Add the powder or gel food coloring towards the end, then mix until the meringue is smooth and uniform. Keep in mind to make the color slightly darker, as it will tend to lighten during baking.
Pour the almond flour and powdered sugar mixture (tant pour tant) over the meringue. Using a spatula, perform the J-fold technique by folding from the bottom up while turning the bowl, to fully combine the dry ingredients with the meringue without deflating the mixture.
Macaronage: Work the batter by pressing it against the sides of the bowl, then gathering it back to the center. Repeat until the mixture becomes smooth, glossy, and flows in ribbons from the spatula, not too runny, but not stiff either.
Note: You can replace the whisk with the paddle attachment (K) of the mixer and use it for macaronnage. Run the mixer on low speed for 10 seconds, then check the texture. It's better to stop just before reaching the final texture, which should flow in a ribbon, and finish with a spatula to avoid ending up with a mixture that's too runny.
Fill a piping bag fitted with a #8 tip, then pipe the macarons into 2 to 3 cm rounds on a baking sheet lined with parchment paper or a silicone mat (like Silpat) with markings. You can also use a template placed under the parchment paper to help guide you, but it's not essential.
Gently tap the underside of the baking sheet or drop it lightly onto the countertop to smooth the shells and release any air bubbles.
Let them rest for 20 to 40 minutes, depending on the humidity level: the surface of the shells should be dry to the touch and no longer stick to your finger.