Heat oven to 375. Spray a 9" x 13" baking pan w/ cooking spray. Cook noodles as directed, drain and cool. Heat oil in lg skillet over medium heat. Cook onion in oil until soft. Add ground turkey. Cook until browned.
Stir in tomato sauce, mushrooms, italian seasonings, pepper and garlic powder. Simmer 2-4 mins. In bowl, combine spinach, ricotta cheese and nutmeg, mix well.
Arrange 3 noodles in bottom of pan. Spread noodles w/ 1/3 of ricotta mix, 1/3 of tukey mix, and 1/3 of mozzarella cheese. Repeat layers, ending w/ mozzarella cheese. Cover pan w/ foil and bake 20 mins. Remove foil and bake 5 more mins.