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 sprayed with cooking spray, ending with sauce.
Bake 25 to 30 min. or until heated through. Top with remaining cheeses; bake 5 min. or until melted.
Prepare using KRAFT 2% Milk Shredded Sharp Cheddar Cheese.
Serve this potato side dish with a crisp, mixed green salad or hot steamed vegetable and cooked lean meat, poultry or fish.
Calories From Fat
% Daily Value*
Total Fat 17g
Saturated Fat 10g
Trans Fat 0g
Total Carbohydrates 34g
Dietary Fiber 4g
* Percent Daily Values are based on a 2,000 calorie diet.
* Nutrition information is estimated based on the ingredients and cooking instructions as described in each recipe and is intended to be used for informational purposes only. Please note that nutrition details may vary based on methods of preparation, origin and freshness of ingredients used.