Sift the powdered sugar and almond flour into a bowl.

To a very clean bowl, add room temperature egg whites.

Using a mixer, whisk the egg whites until they begin to foam. Add cream of tartar and slowly add the granulated sugar as you continue to mix.

Add the food coloring and vanilla, mixing until stiff peaks form. If you want to be like Callie, go with pink macarons.

Fold in 1/3 of the dry ingredients.

Add remaining dry ingredients and fold gently.

The final mixture should be able to fall into a figure eight without breakings. Spoon mixture into your piping bag with the round piping tip.

Pipe 1" dollops onto a baking sheet lined with parchment paper. Tap on the counter several times to release air bubbles.

Allow cookies to sit for about 40 minutes before baking

Preheat oven to 300°F.

Bake cookies for 12-15 minutes, rotating tray halfway through. Cool completely before removing from tray.

In a medium saucepan, combine sugar and water for buttercream filling. Heat over low heat, continuing to stir until sugar dissolves.

Increase heat to medium-high and bring to a boil.

Place egg yolks into a bowl and mix with a whisk attachment until thick and foamy.

When syrup reaches 240°F, remove from heat right away. Slowly drizzle hot syrup into the mixing bowl with the egg yolks.

Continue mixing until the bottom of the bowl is cool to the touch and mixture is room temperature.

Add in butter, one cube at a time, allowing each cube to fully incorporate before adding another. Add vanilla and salt.

Continue mixing about 5-6 minutes or until buttercream is smooth and creamy. Add food coloring if you would like.

Spoon your filling into a piping bag. Pipe your filling onto the back of one of the cookies, placing a second cookie on top, creating a sandwich.

For best results, place in the fridge for 1-3 days before eating.