Easy Cheesy Ham & Potatoes Gratin

Cheesy ham and potato gratin is the casserole built for the days after a holiday spiral ham when half a leftover joint is sitting in the fridge waiting for a job. Sliced cooked potatoes and diced ham go into the dish, and a quick stovetop cheese sauce gets poured over the top before baking until the edges bubble and the cheddar pulls into ribbons.

The sauce is a classic mornay built on a flour-and-butter roux, so it stays glossy and clings to every potato slice instead of breaking. A pinch of nutmeg is the move that separates a proper gratin from a ham casserole. It rounds out the dairy and pulls the savory notes forward without tasting like spice.

Using precooked potatoes shortens the bake to under 40 minutes. The casserole is essentially warming and melting rather than cooking from raw, which is why it’s a smart weeknight play.

Kitchen Tips

• Whisk the milk in gradually, a splash at a time. Dumping it all at once gives you lumpy sauce no matter how much you whisk afterward.
• Use sharp or extra-sharp cheddar. Mild cheddar gets lost behind the ham’s saltiness.
• Slice the cooked potatoes about ¼ inch thick. Thinner and they collapse, thicker and the sauce can’t get between layers.
• Taste before salting. The ham and cheese already bring plenty of sodium, so you may not need much added salt.

Variations

• Swap half the cheddar for Gruyère for a nuttier, more sophisticated flavor.
• Stir in a cup of frozen peas or steamed broccoli florets before baking for a one-dish meal.
• Top with buttered breadcrumbs in the last 10 minutes of baking for a crisp golden crust.