Potato Ham Au Gratin

3.35 from 20 votes

Potato Ham Au Gratin is the ultimate comfort food! Layers of thinly sliced potatoes, diced ham, caramelized onions and a dreamy cheese sauce!

Course Main Course

Cuisine American

Keyword casserole, ham, potato

Prep Time 30 minutes

Cook Time 1 hour 10 minutes

Total Time 1 hour 40 minutes

Servings

Calories 495kcal

1 pound potatoes red skinned, very thinly sliced
1 1/4 cups ham diced
1/3 cup caramelized onions or 1/2 cup yellow onion finely diced
3 tablespoons butter divided
2 tablespoons flour
1 1/2 cups milk
1/4 teaspoon kosher salt
1/8 teaspoon white pepper
1 1/2 cups cheese shredded, I used a 4 cheese Italian blend from Sargento, divided

Preheat the oven to 350.
In a small saucepan, melt 2 tablespoons butter over medium high heat. Add the flour and stir constantly, cooking for about a minute until flour is incorporated and bubbly. Add the salt and pepper and stir until fragrant. Add milk a little at a time, stirring constantly, until the mixture comes to a low boil and thickens. Remove from heat and stir in 1 cup of the cheese until it melts into the sauce. Set aside.
Spray individual gratin dishes or small, shallow casseroles with vegetable spray. Add about a tablespoon of sauce to the bottom of each dish and spread it evenly with the back of a spoon.
Layer the casseroles with 1/3 of the potatoes, followed by the half of the onions and half of the ham. Spoon 1/3 of the sauce over the mixture and spread it evenly with the back of a spoon. Continue to layer the potatoes, onion, ham and sauce, finishing with a layer of potatoes and sauce. Sprinkle the remaining cheese over the casserole. Cut the remaining tablespoon of butter into small cubes and sprinkle them over the cheese. Place the gratins on a baking sheet. Spray a piece of tin foil with vegetable spray and place gently over the casseroles sprayed side down (do not seal the casseroles with the tin foil). Bake for 45 minutes, remove the tin foil and bake for an additional 25 minutes to brown the tops. Serve.