Heat oven to 375°F. Unroll dough on cookie sheet and separate into 4 rectangles; press each into 6x4-inch rectangle, firmly pressing perforations to seal.
Spread 1 tablespoon pizza sauce on half of each rectangle to within 1 inch of edge. Sprinkle each with 3 tablespoons cheese; top with 6 slices pepperoni. Fold dough diagonally over filling; firmly press edges with fork to seal. Sprinkle each triangle with 1/4 teaspoon grated cheese. With fork, prick top of each to allow steam to escape.
Bake 13 to 15 minutes or until deep golden brown. Serve warm.