Slice 2 pepperoni slices in half for the emoji mouths. Cut out 8 hearts from the remaining 2 slices of pepperoni with a small heart-shaped cutter for the emoji eyes.
Place the English muffin halves on a baking sheet and bake until lightly toasted, 5 to 6 minutes.
Spread 1 tablespoon of pizza sauce on each English muffin. Top each with 2 slices of cheese. Arrange the heart eyes and mouth on each pizza. Return to the oven until the cheese is melted, 7 to 10 minutes.