Preheat your oven to 350°F (175°C) and butter a 9×13-inch baking dish.

In a large pot, bring salted water to a boil, add ziti, and cook al dente as per package directions.

Heat olive oil in a skillet over medium-high heat, then add ground Italian sausage. Cook until browned, about 5-6 minutes.

Stir in minced garlic and cook for 1 minute, then add marinara sauce and red pepper flakes. Let simmer for 10 minutes.

Fold the cooked ziti into the sauce, ensuring each piece is coated.

Layer half of the pasta mixture in the baking dish, add half the mozzarella and Pecorino Romano, then layer remaining pasta and cheeses on top.

Bake uncovered for 20 minutes until cheese is melted and bubbly with golden edges.

Remove from oven and let rest for 5-10 minutes. Garnish with fresh parsley before serving.