Baked Pasta Al Forno with Sausage and Peppers

Preheat your oven to 425°F (218°C). Bring 3 quarts of water to a boil in a large pot with 1 tbsp of salt.

Add 8 oz of uncooked rigatoni pasta to the boiling water and cook for 8 minutes (it should be slightly undercooked, as it will finish cooking in the oven). Drain the pasta, reserving 1/2 cup of the starchy pasta water.

While the pasta cooks, prep your vegetables: wash, core, and slice 1 red bell pepper and 1 yellow bell pepper into 1/4-inch strips. Peel and slice 1 yellow onion into thin wedges. Peel and mince 3 garlic cloves. Finely chop 1/4 cup of fresh flat-leaf parsley.

Slice 1 lb of leftover cooked Italian sausage (reserved from Day 1) into 1/2-inch thick rounds.

Heat 2 tbsp of olive oil in a large 12-inch oven-safe skillet (preferably cast-iron) over medium-high heat. Add the sliced red and yellow bell peppers and sliced yellow onion. Sauté for 5 minutes until the vegetables are softened and slightly browned on the edges.

Stir in 3 minced garlic cloves and 1 tbsp of tomato paste. Cook for 1 minute, stirring constantly, until the paste turns a deep brick-red color and smells fragrant.

Pour in 15 oz of canned crushed tomatoes. Stir in 1 tsp of dried oregano, 1 tsp of dried basil, 1/4 tsp of crushed red pepper flakes, 1 tsp of kosher salt, and 1/2 tsp of black pepper. Reduce heat to medium-low and simmer for 5 minutes.

Gently fold the cooked rigatoni pasta, the sliced leftover cooked Italian sausage, and 1/4 cup of the reserved pasta water into the skillet with the sauce. Stir until the pasta and sausage are thoroughly coated.

Tear 6 oz of fresh mozzarella cheese into bite-sized pieces and scatter them evenly over the top of the pasta. Sprinkle 1/2 cup of freshly grated Parmigiano-Reggiano cheese over the mozzarella.

Transfer the skillet directly to the preheated oven. Bake for 10 minutes until the cheese is melted and bubbling. Turn on the broiler for the last 2 minutes to achieve a beautifully caramelized, golden-brown cheese crust.

Carefully remove the skillet from the oven. Let it rest for 5 minutes to set, then garnish with 1/4 cup of chopped fresh parsley before serving.