Cheesy Potatoes Au Gratin with Ham

1: Preheat the oven to 400°F and spray a casserole dish, then set aside.

2: In a saucepan, melt butter and add garlic and flour, whisking until a paste forms. Cook for 1-2 minutes.

3: Add milk and whisk until smooth; then add salt, pepper, thyme, paprika, and mustard.

4: Whisk over high heat until the mixture is thick and bubbly, coating the back of a spoon.

5: Remove from heat, add cheeses, and stir until smooth.

6: Layer half the potatoes and onion slices in the dish, pour half of the cheese sauce over them, and add ham if desired.

7: Repeat with remaining potatoes, onions, and cheese sauce.

8: Sprinkle the top with extra shredded cheese, cover with aluminum foil (sprayed side down), and bake on a baking sheet for 60 minutes.

9: Remove the foil and bake uncovered for an additional 30 minutes until the potatoes are tender and the sauce is bubbly and golden.