1Preheat oven to 400°F. In a 6-qt. stockpot, cook pasta according to package directions for al dente; drain and return to pot.
2In a large skillet, cook sausage, mushrooms, green pepper and onion over medium-high heat 7-9 minutes or until sausage is no longer pink, breaking up sausage into crumbles; drain. Stir in sauce, basil and Italian seasoning. Add to pasta; stir in 2 cups cheese.
3In a microwave, melt butter; stir in garlic. Lightly brush one side of bread with garlic butter. Line bottom and sides of a greased 10-in. spring form pan with bread slices, trimming to fit and facing buttered sides against pan. Fill with pasta mixture; press firmly to pack down. Sprinkle with remaining cheese.
4Bake, uncovered, 25-30 minutes or until golden brown and cheese is melted. Loosen sides from pan with a knife; remove rim. If desired, serve with additional marinara sauce.