How to Make It
Preheat oven to 350°F. Prepare pasta according to package directions, reducing boiling time to 8 minutes.
Cook sausage, peppers, onion, and garlic in hot oil in a 12-inch cast-iron skillet over medium-high, stirring often, until vegetables are soft and sausage has begun to brown slightly, 7 to 8 minutes. Stir in tomatoes, tomato sauce, sugar, salt, and pepper. Bring mixture to a simmer over medium, and add 1/2 cup of the Parmesan, stirring until melted. Stir in cooked pasta. Remove from heat, and sprinkle with mozzarella and remaining 1/4 cup Parmesan.
Bake in preheated oven until mixture is bubbly and cheese is golden, 25 to 30 minutes. Let stand 10 minutes before serving.