01 - Line baking sheets with parchment paper or silicone macaron mats. Fit a large piping bag with a round tip (approximately 1/2 inch diameter). Ensure all equipment is clean and completely dry.
02 - Sift almond flour and powdered sugar together into a large bowl, pressing through any coarse bits that remain in the sieve. Discard any large particles that do not pass through.
03 - In a completely clean, grease-free bowl, beat egg whites with an electric mixer until foamy bubbles form. Add cream of tartar to stabilize the meringue.
04 - Gradually add granulated sugar while continuing to beat on medium-high speed. Continue whipping until stiff, glossy peaks form and the meringue clings firmly to the whisk when lifted.
05 - Add the sifted almond flour mixture to the meringue in three additions. Using a rubber spatula, fold firmly while pressing the batter against the bowl sides. Continue until the batter flows in thick ribbons and you can draw a figure-8 pattern without the stream breaking.
06 - If using color, add gel food coloring now. Fold gently until evenly incorporated. Avoid over-mixing at this stage.
07 - Transfer batter to the prepared piping bag. Hold the bag perpendicular to the baking sheet and pipe 1.5-inch circles, leaving about 1.5 inches of space between each shell.
08 - Firmly tap each baking sheet against the counter several times to dislodge trapped air. Use a toothpick to pop any visible bubbles on the surface for smooth, uniform tops.
09 - Let piped shells rest uncovered at room temperature for 30-60 minutes. The shells are ready when a dry skin has formed and the batter does not stick to your finger when lightly touched.
10 - Preheat oven to 300°F. Bake one tray at a time for 12-15 minutes, rotating the pan halfway through baking. The shells are properly baked when they have developed visible 'feet' and lift cleanly from the parchment paper.
11 - Allow shells to cool completely on the baking sheets before attempting to remove them. This prevents breakage and ensures proper structure.
12 - Beat softened butter in a bowl until creamy and smooth. Add powdered sugar, vanilla extract, salt, and 1 tablespoon of milk. Beat until fluffy and well-combined, adding additional milk only if needed to achieve a smooth, pipeable consistency.
13 - Pair shells by matching similar sizes. Pipe a small dollop of buttercream onto the flat side of one shell. Gently press a matching shell on top, twisting slightly to evenly distribute the filling.
14 - Store assembled macarons in an airtight container and refrigerate for 24 hours before serving. This resting period allows the flavors to meld and creates the characteristic chewy texture. Bring to room temperature before enjoying.