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

Sift the powdered sugar and almond flour together into a large bowl to remove any lumps.

In a clean, dry bowl, beat the egg whites with an electric mixer until soft peaks form.

Gradually add the granulated sugar, one tablespoon at a time, and continue beating until stiff, glossy peaks form.

Add a few drops of red gel food coloring and mix until fully incorporated and evenly colored.

Gently fold the sifted powdered sugar and almond flour mixture into the meringue in small batches. Use a spatula to fold, being careful not to deflate the meringue.

The batter should be smooth and flow like "lava" when dripped from the spatula.

Transfer the macaron batter into a piping bag fitted with a round tip.

Pipe small circles (about 1.5 inches in diameter) onto the prepared baking sheets, leaving space between each macaron shell.

Tap the baking sheets on the counter a few times to release any air bubbles.

Let the macarons rest at room temperature for 30-60 minutes, or until a skin forms on the surface (you should be able to touch them without the batter sticking to your finger).

Bake the macarons for 15-18 minutes, or until the tops are set and the "feet" have formed around the edges.

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

In a bowl, beat the softened butter until creamy.

Gradually add the powdered sugar and vanilla extract, then add the heavy cream or milk. Beat until light and fluffy.

Once the macaron shells have cooled, pair them by size.

Pipe the buttercream filling onto the flat side of one shell and sandwich it with the other.

Use white royal icing or edible white paint to create Santa’s beard and hat trim. Red icing can be used for the hat itself.

Add mini marshmallows for a fluffy beard or to decorate Santa’s hat.

Use black gel food coloring or edible pearls to create Santa's eyes.

Let the decorations set before serving.

Your festive Santa Claus Macarons are ready to enjoy for the holidays!