Nutrition per serving may change if servings are adjusted.
4 cups cold water, divided
1½ cups cornmeal
1¼ teaspoons salt
1 tablespoon olive oil
1 small onion, thinly sliced
4 cups fresh mushrooms, halved
¼ teaspoon ground black pepper
3 medium green bell peppers, roasted and chopped (see Tip)
3 medium red bell peppers, roasted and chopped (see Tip)
1¼ cups marinara sauce
1 cup shredded mozzarella cheese (4 ounces)
Bring 2½ cups water to a boil in a medium saucepan. In a medium bowl, combine the remaining 1½ cups water, cornmeal and 1 teaspoon salt. Slowly add cornmeal mixture to boiling water, stirring constantly. Cook and stir until mixture returns to boiling; reduce heat to low. Cook for about 10 minutes or until mixture is very thick, stirring occasionally. Pour the hot mixture into a 3-quart rectangular baking dish. Cool slightly. Cover and refrigerate about 1 hour or until firm. (Or, cover and refrigerate up to 24 hours.)
Preheat oven to 350°F. Heat oil in a large nonstick skillet, over medium heat. Add onion; saute for 3 to 4 minutes or until tender. Add mushrooms, the remaining ¼ teaspoon salt and the black pepper. Cook and stir for about 5 minutes or until mushrooms are tender. Remove from heat; stir in the green and red roasted peppers.
Spread the marinara sauce over the chilled polenta. Top with the vegetable mixture and sprinkle with mozzarella cheese. Bake, covered, for 30 minutes. Bake, uncovered, for 10 to 15 minutes more or until edges are bubbly.
Tip: To roast peppers, quarter the peppers lengthwise; remove stems, seeds and membranes. Place peppers, cut-sides down, on a foil-lined baking sheet. Roast in a 450-degree F oven for 15 to 20 minutes or until skins are blistered and bubbly. Fold up foil on baking sheet around peppers to form a packet; seal. Let stand for 20 minutes to loosen skins. Peel and chop peppers. (Or substitute three 7-ounce jars or two 12-ounce jars roasted red peppers, drained and chopped, for the green and red roasted peppers.)