Sift almond flour and powdered sugar together at least twice into a large bowl to ensure no lumps, then set aside.

Whip room-temperature egg whites in a clean bowl until foamy, then add cream of tartar and gradually incorporate granulated sugar; continue whipping on high speed until stiff, glossy peaks form, then gently fold in gel food coloring.

Add one-third of the sifted dry ingredients to the meringue and fold gently with a spatula using a 'cut and fold' motion; add the remaining dry ingredients in two more additions, folding until the batter reaches a 'lava-like' or 'ribbon' consistency.

Transfer the macaron batter to a piping bag fitted with a round tip and pipe heart shapes onto baking sheets lined with parchment paper or silicone mats; gently tap the baking sheets to release air bubbles.

Let the piped macarons rest at room temperature for 30-60 minutes, or until a 'skin' forms that you can gently touch without batter sticking.

Preheat your oven to 300°F (150°C) and bake one tray at a time for 12-15 minutes, or until the 'feet' are fully formed and the macarons don't wobble when nudged.

After baking, remove the tray from the oven and slide the parchment paper onto a wire rack to cool completely.

Once the macaron shells are cool, match similarly sized shells, then pipe or spread your desired filling onto one shell and gently sandwich it with another.