Cook tortellini according to package directions. Drain well.
In a large bowl, combine cooked tortellini, pizza sauce, pepperoni, mozzarella cheese, and optional Italian cheese blend, Italian seasoning, garlic powder, and red pepper flakes.
Pour mixture into a greased 9x13 inch baking dish.
Bake for 25-30 minutes, or until heated through and bubbly.
Garnish with fresh basil or parsley before serving.
Notes
Leftovers can be stored in the refrigerator for up to 3 days.