Sift together almond flour and confectioners sugar in a large bowl. Set aside.

In a stand mixer, combine egg whites, white sugar, and egg white powder over a bain-marie and heat to 140°F while whisking.

Remove from heat and whip until stiff peaks form and the mixture is glossy.

Fold the sifted dry ingredients into the meringue until the batter flows in a ribbon-like consistency.

Transfer batter into a piping bag and pipe small circles on a baking sheet.

Let the piped macarons rest until a skin forms, then bake in a preheated oven at 300°F for 15-20 minutes.

Prepare buttercream filling by blending heat-treated cake mix with butter and confectioners sugar, then add heavy cream, vanilla, and food coloring.

Once shells have cooled, pair them and pipe buttercream filling onto one shell, sandwiching it with another shell.

Refrigerate assembled macarons overnight to meld flavors.