Bring a pot of well-salted water to a boil. Cook the Protein+ rotini to just al dente according to the package. Before draining, reserve 1/2 cup pasta water. Keep the drained pasta separate so leftovers do not drink all the sauce.

While the pasta cooks, heat the oven broiler with a rack about 6 inches below the element. Heat a large oven-safe skillet over medium with the olive oil.

Add the orange pepper and onion. Cook for 5 to 6 minutes, stirring occasionally, until softened and browned at the edges.

Stir in the garlic powder, oregano, red pepper flakes, and black pepper for 30 seconds. Add the Rao's marinara and frozen meatballs, turning the meatballs to coat them.

Bring the sauce to a gentle simmer. Reduce the heat to medium-low, cover, and cook for 12 to 15 minutes, stirring halfway through, until the meatballs reach at least 165°F. Add reserved pasta water 1 tablespoon at a time only if the sauce becomes too thick.

Taste before salting. Scatter the mozzarella evenly across the top, followed by the Parmesan. Broil for 2 to 4 minutes, watching continuously, until the cheese bubbles and develops browned spots. Rest for 5 minutes.

Divide the measured rotini among four bowls and spoon the meatballs, sauce, pepper, onion, and browned cheese over it.