Cook spaghetti in boiling water until tender but not mushy. Drain and rinse with cold water.
In a large saucepan cook mushrooms, red peppers, and onion in margarine until tender. Add flour, and stir until blended.
Add chicken broth and stir until smooth and thickened. Add half and half, parsley, garlic powder, and black pepper. Stir in turkey. Add cream mixture to cooked spaghetti and pour into a casserole pan.
Top with parmesan cheese. Bake at 325 degrees for 30 minutes or until golden brown.
