Classic Potatoes Au Gratin

By KSmitherman

Ingredients

• 1/4 cup (1/2 stick) butter or margarine
• 1/4 cup flour
• 1 tsp. salt
• 1/2 tsp dry mustard
• 1/4 tsp pepper
• 2 1/2 cups milk
• 1 pkg. (8 oz.) shredded cheddar cheese
• 2 tbs. chopped onion
• 6 cups thinly sliced peeled potatoes (about 6 to 8 medium)

Preparation

Step 1

Bake at 350
Melt butter in medium saucepan on medium heat. Blend in flour, salt, mustard and pepper. Gradually add milk, stirring until well blended; cook until thickened, stirring constantly.
Add 1 1/2 cups of the cheese and the onion; cook until cheese is melted, stirring frequently. Layer potatoes and cheese sauce alternately in 2 quart casserole dish, ending with a layer of cheese sauce.
Bake 1 hour and 15 minutes or until potatoes are tender. Sprinkle with the remaining cheese. Bake an additional 5 minutes or until cheese is melted.