Potatoes au Gratin

Potatoes au Gratin


What You Need

2-1/2 lb. baking potatoes (about 6)
1/4 cup (1/2 stick) butter
1 small onion, chopped
1/4 cup flour
1 tsp. salt
2-1/2 cups milk
1-3/4 cups Shredded Sharp Cheddar Cheese, divided
1/2 tsp. Dijon Mustard
1/4 cup Grated Parmesan Cheese

Make It

COOK potatoes in boiling water 20 min. or just until tender; drain. Cover with cold water; cool.

MEANWHILE, melt butter in medium saucepan on medium heat. Add onions; cook and stir 2 min. Blend in flour and salt; cook 1 min. Gradually stir in milk; cook 5 min. or until thickened, stirring constantly. Add 1-1/4 cups cheddar; cook and stir 1 min. or until melted. Stir in mustard.

HEAT oven to 375°F. Peel potatoes; cut into 1/4-inch-thick slices. Layer alternately with cheese sauce in 2-qt. casserole, ending with sauce.

BAKE 25 to 30 min. or until heated through. Top with remaining cheeses; bake 5 min. or until melted.