Preheat oven to 450°.
Arrange polenta slices in the bottom of an 11 x 7-inch baking dish coated with cooking spray. Bake at 450° for 8 minutes, turning once.
While the polenta bakes, heat a large nonstick skillet coated with cooking spray over medium-high heat. Remove casings from sausage. Place sausage, bell pepper, and fennel seeds in pan; cook 5 minutes or until the sausage is browned, stirring to crumble. Add seasoning and tomatoes; cook 2 minutes or until thoroughly heated. Pour the sausage mixture over polenta, and top with cheese. Bake at 450° for 3 minutes.