In a skillet, cook sausage, onion and green pepper over medium-high heat until meat is no longer pink; drain. Stir in the 2 tablespoons flour, the basil, and fennel seed.
Add tomato sauce. Bring to a boil; cook and stir for 1 minute. Transfer to an ungreased 9x13-inch baking dish. Sprinkle with mozzarella cheese. Place remaining flour in a mixing bowl. Beat in the eggs, milk, oil, and salt until smooth; stir in Parmesan cheese. Pour over casserole. Bake uncovered, at 425 degrees for 25 to 30 minutes or until browned.