Mushroom Zucchini au Gratin

Name: Mushroom Zucchini au Gratin
Prep time: 30 min
Cook time: 15 min
Total time: 45 min
Cuisine: European, Mediterranean, French
Ingredients: 1 lb (16 oz) fresh mushrooms, (sliced); 1 medium onion, (diced); 1 large zucchini, (sliced ); 4 tablespoons butter; ⅔ cups sour cream; 2 tablespoons flour; ½ teaspoon salt; ½ teaspoon garlic powder; ⅛ teaspoon black pepper; ⅛ teaspoon paprika; ½ cup fresh chopped parsley; ½ cup shredded Gruyère cheese; ½ cup shredded Swiss cheese