Ingredients
- 4 1/2 tablespoons butter
- 1 small yellow onion finely diced
- 4 1/2 tablespoons all-purpose flour
- Kosher salt to taste
- Ground black pepper to taste
- 1 1/2 teaspoons Dijon mustard
- 2 cups low-fat milk
- 2 1/4 cups cheddar cheese shredded, divided
- 6 medium russet potatoes peeled and thinly sliced
- 2 cups diced cooked ham
- Fresh parsley chopped (for garnish)
Instructions
- Preheat oven to 350°F. Lightly grease a 9x13-inch baking dish.
- In a skillet over medium heat, melt the butter. Add the chopped onion and cook until soft, about 5 minutes. Stir in flour, salt, and pepper, and cook for 1 minute.
- Gradually whisk in the Dijon mustard and milk until the sauce thickens. Gradually stir in 2 cups of the cheddar cheese, a little bit at a time, until just melted. If the sauce seems thin, you can add more cheese as needed.
- In the prepared baking dish, layer half of the potatoes, half of the diced ham, and half of the sauce. Repeat by layering the remaining potatoes, ham, and sauce. Sprinkle the remaining 1/4 cup of cheese over the top.
- Cover the dish with foil and bake for 60 minutes. Remove the foil and continue baking until the top turns golden and the potatoes become tender, about another 25-30 minutes.
- Remove the dish from the oven and let it rest for 5 minutes.
- Sprinkle with fresh parsley, if desired. Serve warm.
