Preheat oven to 425°. In a large skillet, saute onion and green pepper in 2 tablespoons oil until tender. Stir in 2 tablespoons flour, basil and fennel until blended. Add spinach, mushrooms and tomato sauce. Bring to a boil; cook and stir 2 minutes or until thickened.
Pour into a greased 11x7-in. baking dish. Sprinkle with cheddar cheese. Place the remaining flour in a large bowl. Add eggs, milk, salt and remaining oil; beat until smooth. Stir in Parmesan cheese. Pour over vegetable mixture.
Bake, uncovered, 20-25 minutes or until a thermometer reads 160°.