Ingredients

• cooking spray
• 8 medium potatoes , peeled and thinly sliced
• 0.5 cups butter
• 1 onion , finely chopped
• 0.5 cups all-purpose flour
• 2 teaspoons Dijon mustard
• 1 teaspoon salt
• 0.25 teaspoons ground black pepper
• 3 cups milk
• 2 cups shredded Cheddar cheese
• 3 cups diced ham

Instructions

1. 1 Gather all the ingredients. Preheat the oven to 350 degrees F (175 degrees C). Spray a 9x13-inch baking dish with cooking spray.
2. 2 Bring a large pot of water to a boil. Add potatoes and cook until almost tender, 5 to 10 minutes. Transfer to a colander and rinse with cold water until cool enough to handle. Drain well and set aside.
3. 3 Melt butter in a large skillet over medium heat. Add onion; cook and stir until tender, about 5 minutes. Stir in flour, Dijon mustard, salt, and pepper; cook for 1 minute. Gradually pour in milk, stirring constantly until sauce is thickened, about 5 minutes. Stir in Cheddar cheese until melted.
4. 4 Layer ½ of the potatoes in the bottom of the prepared baking dish. Top with 1 ½ cups diced ham and ½ of the Cheddar cheese sauce. Repeat another layer with remaining potatoes, ham, and sauce.
5. 5 Bake in the preheated oven until the sauce is bubbling and the top of the casserole is golden brown, about 1 hour.

Nutrition per serving