To prepare the marinara, heat oil in a medium saucepan and sauté garlic and onions for 2 to 3 minutes. Remove the shiitake and maitake from the soaking water. Save the water for soup stock. Chop the maitake coarsely. Add the shiitake and maitake to the saucepan and sauté another 2 to 3 minutes. Add the spaghetti sauce and basil. Cover and simmer for 20 minutes or until the maitake are tender.
While the sauce is cooking, prepare the polenta by bringing the water and salt to a boil. Whisk in the polenta, stirring constantly until it thickens. Reduce the flame to low and simmer for 15 to 20 minutes. If using finely ground polenta, reduce the water by 1 cup and cook 10 minutes. When the polenta is done, place on individual serving plates and ladle the sauce over each serving.
Per serving - 286 calories, 9 g fat (22% calories from fat), 12 g protein, 59 g carbohydrate, 20 g fiber, 0 mg cholesterol, 394 mg sodium