Sift the almond flour and powdered sugar together in a bowl to remove lumps.

In a clean mixing bowl, beat the egg whites until foamy. Add cream of tartar and continue beating until soft peaks form.

Gradually add granulated sugar while beating until stiff peaks form. The mixture should be glossy.

If desired, add food coloring and gently fold in the sifted dry ingredients in three additions until the batter flows like lava.

Transfer the batter into a piping bag fitted with a round tip. Pipe small circles on a baking sheet lined with parchment paper.

Let the macarons rest at room temperature for 30-60 minutes until a skin forms on the surface.

Preheat the oven to 300°F (150°C). Bake the macarons for 15-20 minutes until they have risen and developed feet.

Let the macarons cool completely on the baking sheet before removing them.

In a saucepan over medium heat, cook the raspberries until syrupy, about 5 minutes. Strain to remove seeds and let cool.

In a mixing bowl, beat the softened butter until creamy. Gradually add powdered sugar and mix until light and fluffy.

Mix in the cooled raspberry puree and vanilla extract until well combined.

Pair up macaron shells by size. Pipe raspberry filling onto the flat side of one shell and sandwich with another shell.

Refrigerate the assembled macarons for at least 24 hours to allow flavors to meld.