Preheat oven to 350 Farenheit
Spray a 3 quart casserole dish with nonstick spray
Cook rotini according to instructions until al dente and drain
Add to casserole dish and set aside
Brown sausage crumbles and drain
Add sausage crumbles to casserole dish
Pour pasta sauce, 1/2 the cheese, and half the pepproni into the casserole dish
Stir to combine and spread casserole evenly in dish
Top with remaining pepperoni and cheese
Bake covered for 40 minutes and finish baking uncovered for 5 minutes