Portabella mushrooms serve as edible plates on which you stack mouthwatering vegetables and gooey mozzarella cheese (smoked mozzarella is good too). This recipe is thanks to the American Heart Association.
Preheat the oven to 400*F. Lightly spray a nonstick baking sheet with vegetable oil spray. Lightly spray both sides of the mushrooms with vegetable oil spray; place with the stem side up on the baking sheet.
Bake for 12 minutes, or until fork tender. Set aside.
Meanwhile, heat a large nonstick skillet over medium-high heat. Remove from heat and lightly spray with vegetable oil spray (being careful not to spray near a gas flame). Cook the zucchini, bell peppers, onion, and basil for 5 minutes, or until the zucchini is tender. Stir in the tomato sauce, sugar, salt, and red pepper flakes; cook for 4 minutes, or until thickened, stirring frequently.
Spoon 1/2 cup zucchini mixture over each mushroom; top with the mozzarella cheese.
Bake for 5 minutes, or until the mozzarella has melted. Remove from oven. Sprinkle with the Parmesan.