You won’t need a special heart-shaped muffin tin to make these muffins.

Materials:
Your favorite muffin recipe
Muffin tins
Muffin or cupcake liners
Marbles or marble-sized rolled up balls of foil.

Line the muffin tins with the liners and prepare your favorite muffin or cupcake recipe. Fill the liners with the batters.  Place the marble or foil between the liner and the edge of the muffin tin. Bake as usual. As the muffin bakes the batter will pull away from the sides and form a heart shape.