Preheat oven to 375°F. Grease a 9x13 inch baking dish.
Cook pasta al dente according to package directions; drain.
In a large bowl, mix pizza sauce, marinara sauce, heavy cream, garlic powder, Italian seasoning, onion powder, salt, and pepper until smooth.
Add cooked pasta and 1 cup mozzarella cheese. Toss to combine.
Transfer to prepared baking dish. Top with remaining 1 1/2 cups mozzarella cheese, then arrange pepperoni slices on top.
Cover with foil and bake 20 minutes. Remove foil and bake 8–10 minutes more until cheese is bubbly and golden.
Serve hot.
Notes
Pro Tip:
Cook pasta just until al dente, since it will continue cooking in the oven. If using gluten-free pasta, undercook slightly, as it softens faster and can become mushy.