Preheat oven to 375°F; grease a 9x13-inch dish.
Cook pasta according to package until al dente; drain and set aside.
Brown sausage in a large skillet over medium, crumbling; drain excess fat.
Combine pasta, sausage, marinara, 1 cup mozzarella, half the pepperoni, Parmesan, Italian seasoning, garlic powder, and optional olives in a large bowl.
Pour into dish; top with remaining mozzarella and pepperoni.
Bake 25-30 minutes until cheese melts and bubbles; stand 5 minutes and garnish with fresh basil before serving.