Preheat the oven to 400°F. Add the olive oil into a 9x13-inch casserole dish and spread it around so it coats the bottom and sides. Set aside.
1 tablespoon olive oil
In a large skillet, over medium-high heat, cook and crumble the ground Italian sausage until it is no longer pink and fully browned; about 6-8 minutes. Drain or soak up any leftover grease from the skillet.
1 pound ground mild Italian sausage
Add the pizza sauce, garlic powder, Italian seasoning, kosher salt, and black pepper into the skillet. Stir well, and then let the mixture simmer for 8-10 minutes, until everything is blends together and it slightly thickens.
24 ounces pizza sauce, 1 teaspoon garlic powder, 1 teaspoon Italian seasoning, ½ teaspoon kosher salt, ¼ teaspoon black pepper
Evenly spread the pizza sauce meat mixture into the prepared casserole dish.
Arrange the frozen tater tots in an even layer over top, making sure to keep them snug but not stacked.
1 bag (32 oz) frozen tater tots
Sprinkle the shredded mozzarella cheese over top the tater tots.
8 ounces whole milk mozzarella cheese
Lay out as many pepperoni slices as you like across the top of the shredded cheese.
1 package (6 oz) sliced pepperoni
Bake, uncovered, for 35-40 minutes.*When done, the edges should be bubbling, the cheese will be melted and golden brown, and the pepperoni begins to cup and become crisp at the edges. The casserole should also feel firm and set when gently pressed in the center. Remove the tater tot casserole from the oven and immediately sprinkle the grated parmesan cheese over top. Let it rest for 5 minutes before serving hot. Enjoy!
1/4 cup grated parmesan cheese