Bring a large pot of lightly salted water to a boil. Add pasta and cook for 8 to 10 minutes or until al dente; drain. Set aside in warm water.
In a large heavy skillet saute mushrooms, garlic and onions. Add ground turkey and cook until evenly brown. Season with salt and pepper. Remove from heat, and stir in spinach, parsley, cottage cheese and Parmesan cheese.
Stuff the cooked shells with the mixture, and place in a 9x13 inch baking dish. Cover with spaghetti sauce, and sprinkle top with mozzarella cheese.
Cover with foil, and bake in preheated oven for 30 to 45 minutes, or until heated through.