Scalloped potatoes with ham layers thin-sliced potatoes and diced ham in a creamy cheese sauce baked until golden. This protein-rich, family-favorite casserole is a holiday staple and leftover ham's best friend.
Preheat oven to 375°F (190°C). Grease a 9x13-inch casserole dish with butter or nonstick spray.
Peel and slice the potatoes thinly (about 1/8 inch thick) for even layering and tenderness.
In a saucepan over medium heat, melt butter and sauté finely chopped onion until soft, about 4 minutes. Stir in flour and cook, whisking constantly, for 1 minute.
Gradually pour in milk, whisking to avoid lumps. Add salt, pepper, garlic powder, and paprika. Cook over medium heat until mixture thickens, about 4–5 minutes.
Remove from heat and whisk in shredded cheddar cheese until smooth and melted.
Layer half of the sliced potatoes in the prepared dish. Scatter half the diced ham over potatoes. Pour half of the cheese sauce evenly over the top.
Repeat with remaining potatoes and ham, then cover with the rest of the sauce, ensuring even coverage.
Cover the casserole with foil and bake for 45 minutes. Remove foil and bake an additional 25–30 minutes, until top is bubbling and deeply golden.
Let rest for at least 15 minutes out of the oven to allow sauce to thicken before serving.
Sprinkle with extra black pepper, paprika, or chopped parsley if desired before serving.