Spray a baking sheet with cooking spray. Place frozen rolls on top to thaw. Cover with plastic wrap or a tea towel and let thaw and rise, 3 to 5 hours.
Preheat oven to 350 degrees F (175 degrees C). Uncover rolls.
Bake in the preheated oven until golden brown, about 15 minutes. Transfer to a plate.
Heat olive oil in a large skillet over medium-high heat. Add onion and cook until fragrant, about 2 minutes. Add sausage. Cook, breaking up as you stir occasionally, until browned, 5 to 7 minutes. Stir in 1/2 cup marinara sauce, 1/2 teaspoon garlic powder, onion powder, Italian seasoning, and red pepper flakes. Cook until heated through, about 4 minutes. Transfer mixture to a bowl.
Pour remaining marinara sauce into a microwave-safe bowl. Cook in the microwave until heated through, about 1 minute.
Combine remaining 1/2 teaspoon garlic powder, ricotta cheese, 3/4 cup mozzarella cheese, Parmesan cheese, eggs, salt, and pepper in another microwave-safe bowl. Microwave on high for 2 minutes and stir. Continue to microwave until completely heated through, about 2 minutes more. Stir in parsley.
Slice rolls in half and place on a plate. Serve with the bowls of sausage mixture, marinara sauce, cheese mixture, and the pepperoni, layering as you please.