Through a fine sieve into a large bowl add almond flour and confectioners’sugar. Sift and discard large lumps. Mix thoroughly, by hand, until all visible lumps disappear.
In a stand mixer with whisk attachment, add egg whites and whip until frothy (one minute max.), then add cream of tartar. Whip to soft peaks, then add granulated sugar. Whip until glossy and stiff peaks.
Fold dry blend into egg whites, one third at a time until just mixed. (If not adding color, mix until batter flows from sides of bowl into center, like lava). Otherwise, divide batter into three separate bowls. Add a few drops of your favorite food gel colors to each. Fold color in, do not over mix. Batter should flow like lava.
Fill each 12" piping bag with macaron batter. Snip ends and place all three bags inside 20" piping bag fitted with large round piping tip. Slightly shake bag to pool batters towards piping tip, then trim excess piping bag around piping tip. (Be careful not to trim too much or tip may fall out).
Prepare a baking sheet pan with macaron mat or if using a silpat insert a template under it. Pipe your batter using light pressure and quickly releasing pressure before pulling tip away from mat.
Preheat oven to 330 degrees. Remove template if used and tap tray on counter space about 5 times to release air bubbles. Allow macs to dry at room temp for 30-60 minutes. Macs are ready to bake when dry to the touch. Bake at 330 degrees for 12 minutes.
Before removing from oven, check your macs to see if they move when touched. If they do, they are not baked enough, close door and check again in 2 minutes. Transfer pan to a wire rack and allow to completely cool (about 10-15 minutes). If macs stick to silpat/mat, they are under-baked. Return to oven with heat off and door slightly ajar. Recheck after 5 minutes.
Pipe your fave buttercream filling onto one mac and top with another; I recommend Swiss Meringue. Insert a lollipop stick for mac pops. Or Pipe a thin border of Swiss meringue and add a dollop of fruit preserves in center and top with another mac. YUM! Enjoy.