Preheat your oven to 300°F (150°C). Line two baking sheets with parchment paper or silicone mats.

Sift together almond flour and powdered sugar twice to aerate. Discard any lumps.

In a clean bowl, whip egg whites until frothy. Gradually add granulated sugar, cream of tartar, and salt until soft peaks form.

Increase mixer speed to high, whip until stiff peaks form. Add gel food coloring at the soft peak stage.

Fold the sifted dry ingredients into the meringue using a spatula until a thick, lava-like consistency is achieved.

Transfer batter to a piping bag and pipe onto lined baking sheets in 1.5-inch circles.

Tap sheets gently on counter to release air bubbles. Allow piped macarons to rest for about 15 minutes.

Bake for 15-18 minutes until firm. Do not over-bake.

Let macarons cool completely on the baking sheets for about 10-15 minutes.

Prepare buttercream filling by whisking together egg yolks and sugar until fluffy, slowly add cream and cook until thickened. Mix in butter and flavor.

Assemble macarons by pairing shells and piping buttercream onto one, sandwiching with another shell.

Refrigerate filled macarons in an airtight container for 24 hours for optimal flavor.