Sift almond flour and powdered sugar together and set aside.

Whip egg whites with cream of tartar until foamy, then add granulated sugar and beat to stiff peaks.

Add gel food coloring and mix until evenly combined.

Fold dry ingredients into the meringue until the batter flows smoothly.

Pipe heart shapes onto a lined baking sheet and tap to remove air bubbles.

Rest shells until dry to the touch, then bake at 300°F for 14 to 16 minutes.

Cool shells completely before filling.

Beat butter, powdered sugar, vanilla, and cream to make buttercream.

Sandwich shells with filling and serve.