Two-Potato Gratin Recipe - BettyCrocker.com

Ingredients

• 1/4 cup butter or margarine
• 1/4 cup Gold Medal™ all-purpose flour
• 2 cups milk
• 1 teaspoon Dijon mustard
• 1/2 teaspoon salt
• 1/4 teaspoon pepper
• 4 oz smoked Gruyère cheese, shredded (1 cup)
• 1 cup shredded white Cheddar cheese (4 oz)
• 1 1/4 lb unpeeled Yukon Gold potatoes (3 to 4 large), cut into 1/4-inch slices
• 2 medium sweet potatoes, peeled, cut into 1/4-inch slices (1 1/2 lb)