Sift the powdered sugar and almond flour into a bowl.

In a separate bowl, whisk the egg whites on low speed, gradually increasing to medium-high until soft peaks form.

Slowly add the granulated sugar while whisking until stiff peaks form.

Gently fold in the almond flour mixture, adding food coloring if desired, until it looks like thick lava.

Transfer the batter to a piping bag fitted with a round tip. Pipe heart shapes onto a parchment-lined baking sheet.

Let the piped macarons rest at room temperature for 30 minutes to 1 hour.

Preheat the oven to 300°F (150°C) and bake for 18 to 20 minutes until firm to the touch.

In a mixing bowl, beat the softened butter until smooth.

Gradually mix in the powdered sugar until combined.

Stir in the vanilla extract, salt, and add heavy cream until smooth. Mix in food coloring if desired.

Once cooled, flip the macaron shells over and pipe buttercream onto one shell, then sandwich with another shell.

For best results, chill in the fridge for at least 24 hours before serving.