Preheat oven to 300°F, with rack placed in the lower section of the oven. Fit baking sheets with parchment paper or silicone mats. Make sure the pans are flat (not dented or warped) and the parchment is trimmed to fit pan. Using paper templates, trace circles onto the parchment or place them under the silicone mats.

In the bowl of a food processor fitted with a metal blade, process confectioners’ sugar and almond flour into a fine powder, about 30 seconds. Using a drum sieve, sift mixture onto a sheet of parchment paper three times and discard any coarse meal (no more than ½ teaspoon). Set aside.

To make the meringue: To the bowl of a stand mixer fitted with a whisk attachment, add egg whites and cream of tartar; whip whites on medium speed until foamy. Gradually add sugar, stopping to scrape down the sides of the bowl as needed. Once all the sugar is incorporated, continue to whip meringue into stiff glossy peaks. The meringue should have the consistency of shaving cream. Whisk in about ¼ teaspoon of food coloring, adding more as needed until the desired color is achieved. The meringue should remain thick and stable.

To complete the macaronnage step: Add one-third of the sifted flour mixture to the meringue and fold with the spatula. Once incorporated, add the remaining flour mixture, smearing the batter along the sides of the bowl and then folding back to the center, being careful not to over mix. Repeat until the batter becomes shiny and reaches the consistency of slow moving lava. To check for the correct consistency, the batter should flow from your spatula like thick lava and hold a ribbon for a couple of seconds, then fall back into itself making a smooth glossy surface. If it falls in clumps and doesn’t flow slowly, continue to fold gently, deflating the batter until the proper consistency is reached.

Transfer batter to a pastry bag fitted with a ½-inch plain round tip. Pipe a small dollop of batter into the corners of each baking sheet and lay parchment over (ink side down) and press down corners to secure. Using both hands to hold the pastry bag, pipe batter by placing the tip ½-inch above the parchment, directly in the center of the first stenciled circle, and fill. Once the circle is filled, stop squeezing and make a quick upward and sideways motion to detach the batter and move to the next circle. (The batter should settle into a smooth and glossy round circle.)

Let macarons stand at room temperature until a firm skin forms on the macarons, 30 to 45 minutes. To check to see if the macarons are ready, lightly touch the side, and if your finger does not make a dent, they are ready for the oven.

Bake macarons one sheet at a time, rotating halfway through, until macarons are crisp and firm, 14 to 16 minutes. Carefully slide macaron topped parchment sheets onto a wire rack and allow macarons to cool completely before removing from paper and filling.

To assemble: Pipe a cherry-size portion of buttercream into the center of the flat side of a cooled macaron. Place another cookie, flat side down, over the filling and gently press just enough to push the filling out towards the edges. Once filled, macarons can be refrigerated in an airtight container up to 3 days.