Arrange 2 racks evenly in oven. Preheat oven to 450°F. Line two baking sheets with foil; set aside.
Divide dough into 4 equal size balls. Roll and stretch one of the dough balls into an oval. Using kitchen shears, snip a 1/4- to 1/2-inch into the top of the oval to make the top of the heart. Using your hands, shape the dough into a heart and gently transfer to one half of a prepared pan. Stretch dough again to correct shape.
Spread 2 Tbs. of sauce evenly over the crust and sprinkle with 1/3 cup mozzarella. Place 8 of the pepperoni hearts over the cheese. Repeat with the remaining dough, sauce, cheese and pepperoni, placing two hearts on each pan.
Transfer baking sheets to the oven and bake until bubbly and golden brown, about 12 to 15 minutes.