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

In a separate bowl, beat egg whites with cream of tartar until soft peaks form. Gradually add granulated sugar and continue beating until stiff, glossy peaks form.

Add red food coloring to the meringue and mix gently until combined.

Gently fold the dry ingredients into the meringue in two additions. Macaronage to the correct consisteny.

Transfer the batter to a piping bag fitted with a round tip. Pipe heart shapes onto baking sheets lined with parchment paper or silicone mats.

Tap the baking sheets firmly on the counter several times to release any air bubbles. Let the macarons rest at room temperature for 30-60 minutes, or until a skin forms.

Preheat oven to 300°F (150°C). Bake for 12-15 minutes, or until the feet are well risen and the shells are set.

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

In a bowl, beat the softened butter until light and fluffy. Gradually add powdered sugar and beat until smooth.

Add raspberry puree and mix until combined.

Pipe or spread raspberry buttercream filling onto one macaron shell. Top with another macaron shell to create a sandwich.

Repeat with the remaining shells and filling.

Refrigerate the macarons for at least 24 hours to allow the flavors to meld.