Name: Au Gratin Potatoes
Prep time: 20 min
Cook time: 90 min
Total time: 110 min
Yield: 8 servings
Ingredients: 2.5 lbs red potatoes; 1 onion; 3 tablespoons butter; 3 tablespoons flour; 1 teaspoon dry mustard; 2 cups milk; 1 cup cheddar cheese; 1/2 cup gruyere cheese; salt & pepper to taste