Sift the powdered sugar and almond flour into a bowl to ensure there are no lumps. Set aside.

In a separate mixing bowl, whisk egg whites until soft peaks form. Gradually add granulated sugar and whisk until stiff peaks form.

Gently fold in the sifted almond flour and powdered sugar mixture using a spatula. Add a few drops of food coloring if desired.

Transfer the batter into a piping bag with a round tip. Pipe heart shapes on a baking sheet lined with parchment paper.

Let them sit for 30 minutes to 1 hour to form a dry skin.

Preheat your oven to 300°F (150°C) and bake the macarons for 18 to 20 minutes.

Beat the softened butter until smooth. Gradually add powdered sugar, mixing well.

Stir in vanilla extract and a pinch of salt.

Add heavy cream one tablespoon at a time until you reach a smooth consistency. Optionally, mix in a few drops of red food coloring.

Once the shells are cool, flip half of them over. Pipe some buttercream on the flat side and sandwich with another shell.

For the best flavor, refrigerate the assembled macarons for at least 24 hours.