Polenta lasagna with creamy mushroom sauce

From Veg times

• 1 medium-size onion, halved and thinly sliced crosswise (1 cup)
• 8 oz. button mushrooms, sliced
• 8 oz. shiitake mushrooms, stems removed and caps thinly sliced
• 2 cloves garlic, minced (about 2 tsp.)
• 3/4 cup plus 2 Tbs. low-fat milk
• 2 Tbs. cornstarch
• 1/4 cup reduced-fat cream cheese, softened
• 1/4 cup dry white wine or low-sodium vegetable broth
• 3/4 tsp. salt
• 1/4 tsp. freshly ground pepper
• 1/4 tsp. ground nutmeg
• 2 17-oz. tubes polenta, cut into 1/2-inch slices (or cook your own)
• 1/2 cup grated Parmesan cheese

1. Preheat oven to 375F. Cook onion in large nonstick skillet coated with cooking spray over medium-high heat 3 minutes, stirring often. Add all mushrooms and garlic; cook, stirring often, 3 to 4 minutes, or until onion is tender. Add 3/4 cup milk, and bring to a simmer, stirring occasionally.
2. Mix cornstarch with remaining 2 Tbs. milk, and stir into mushroom mixture. Add cream cheese and wine, and cook, stirring often, 1 to 2 minutes, or until smooth and blended. Remove from heat. Add salt, pepper and nutmeg.
3. Coat 10x10-inch baking dish with cooking spray. Spread 3 Tbs. mushroom sauce in bottom of dish. Layer 1/3 of polenta slices over sauce. Sprinkle 1/4 cup Parmesan cheese over polenta. Top with half of remaining mushroom sauce. Layer with 1/3 of polenta slices and remaining sauce, and top with remaining polenta.
4. Bake, uncovered, 35 to 40 minutes, or until bubbly. Sprinkle lasagna with remaining 1/4 cup Parmesan. Broil 3 to 5 minutes, or until cheese is lightly browned. Remove from heat. Cover loosely with foil, and let stand 10 minutes before serving.