Preheat your oven to 300°F (150°C)., Line baking sheets with parchment paper. You can outline heart shapes using stencils if you desire uniform sizes., Prepare your piping bag by cutting the tip into a small opening, about ¼ inch in diameter., Sift together the almond flour and powdered sugar in a mixing bowl., In a separate bowl, whip the egg whites, starting on low speed until foamy. Gradually add the granulated sugar while increasing the speed to medium., Once the mixture resembles soft peaks, add the cream of tartar and continue whipping until stiff peaks form., Gently fold the flour mixture into the egg whites using a spatula until you achieve a glossy batter that flows smoothly., In a mixing bowl, beat the softened butter until creamy. Gradually mix in the powdered sugar and beat until bright and fluffy., Add milk or heavy cream to achieve your desired consistency, then stir in vanilla extract and any optional food coloring or flavoring., Using a piping bag, pipe a small amount of filling onto the center of half of your macaron shells, leaving a small border., Place a second shell atop each filled one, gently pushing down to create a sandwich., Dust the completed macarons with a light sprinkle of powdered sugar or additional cocoa powder for a hint of elegance., Arrange your macarons on a plate or in a decorative box for gifting.