. Preheat the Oven:

1. Preheat your oven to 450°F.
2. Place the sausage links on a sheet pan, drizzle with olive oil, and rub to coat evenly.
3. Roast for about 12 minutes, or until just cooked through.
4. Transfer to a cutting board, cool slightly, and slice into ¼-inch pieces.

2. Cook the Rigatoni:

1. Bring a large pot of salted water to a boil.
2. Add rigatoni and cook for 2 minutes less than the package instructions.
3. Reserve ½ cup pasta water, then drain the rigatoni.

3. Prepare the Sauce:

1. Heat ¼ cup olive oil in a large pot over medium-high heat.
2. Add sliced sausage and cook for 2-3 minutes until browned.
3. Stir in cherry tomatoes and a pinch of salt, cooking for another 3 minutes until tomatoes burst.
4. Add garlic, oregano, and red pepper flakes, stirring to combine.
5. Pour in marinara sauce and add fresh spinach, letting it wilt as the sauce simmers.
6. Stir in grated Parmesan cheese until melted and creamy.

4. Combine the Pasta and Sauce:

1. Add the cooked rigatoni, reserved pasta water, and chopped parsley to the sauce.
2. Stir to coat the pasta evenly.

5. Assemble the Casserole:

1. Grease a 12-inch cast iron skillet or a 9×13-inch baking dish with olive oil.
2. Pour half of the pasta mixture into the dish and top with half of the shredded mozzarella cheese.
3. Add the remaining pasta mixture and top with sliced fresh mozzarella and the remaining shredded mozzarella cheese.

6. Bake the Dish:

1. Bake in the preheated oven for 8 minutes, or until the cheese is melted.
2. Broil on high for 1-2 minutes until the cheese is golden and bubbly.

7. Serve and Garnish:

1. Remove from the oven and let cool slightly.
2. Garnish with chopped parsley and additional Parmesan cheese.
3. Serve warm and enjoy!