Heat oven to 375°F.
If using crescent rolls: Unroll dough; separate dough into 4 rectangles. Firmly press perforations to seal. Press or roll into four 7x5-inch rectangles. If using dough sheet: Unroll dough; cut into 4 rectangles. Press or roll into four 7x5-inch rectangles.
Arrange 9 pepperoni slices in center third of each rectangle. Spread 1 tablespoon spaghetti sauce over pepperoni.
Fold each slice of cheese in half; place over pepperoni. Fold short sides of dough to almost meet in center; securely pinch edges together, leaving middle open. Tuck 4 or 5 pepperoni slices into middle opening. Place on ungreased cookie sheet.
Bake 13 to 16 minutes or until golden brown.