1Position the rack in the center of the oven and preheat the oven to 350*F.
2Crumble the sausage meat into a large saucepan and brown over medium heat, stirring often, about 4 minutes.
Drain off any fat, then add the onion and bell pepper. Cook, stirring often, until softened, about 3 minutes.
3Stir in the tomatoes, peas, tomato paste, oregano, basil, thyme, fennel seed, salt, and pepper. Bring to a simmer, then reduce the heat and cook uncovered 5 minutes, stirring often. Stir in the cooked pasta and half the cheese.
4Spread evenly in a 9x13 inch baking pan. Top evenly with the remaining cheese. Bake until the cheese has melted and the casserole is bubbling, about 20 minutes. Let stand 10 minutes at room temperature before slicing into 8 pieces.