In an 11- to 12-inch nonstick frying pan over medium-high heat, combine 1 cup chopped onion, 1/3 pound sliced mushrooms, and 1/4 pound ground turkey. Stir often until mushrooms are lightly browned, about 10 minutes. Add 1/4 pound (2 1/2 cups packed) washed spinach leaves; stir often until wilted, 3 to 4 minutes. Meanwhile, beat 8 large eggs to blend. Turn heat to low, pour eggs into pan, and sitr until eggs are creamy, 2 minutes, or as set as you like. Sprinkle with 2 to 3 tablespoons shredded parmesan cheese and season with salt and pepper.