Cheesy Baked Potato Casserole with Ham Step-by-step instructions

Before you start

Before you begin cooking, gather all your ingredients and prep them to ensure a smooth, stress-free process. Start by peeling and dicing the potatoes into uniform half-inch cubes so they cook at the same rate. Measure out the diced ham, seasonings, and mozzarella cheese.

Ensure your béchamel sauce is ready to pour, whether using store-bought or a prepared batch. Finally, grease your 9x13-inch glass baking dish with cooking spray or butter, and preheat your oven to 375°F (190°C).

Instructions

Prepping the Potatoes and Ham

1. 1Parboil the Potatoes
   Bring a large pot of salted water to a boil. Add the cubed potatoes and cook for 8 to 10 minutes, until they are slightly tender but still hold their shape. Drain them thoroughly and transfer them to a greased 9x13-inch glass baking dish.
   Look for The potatoes should be easily pierced with a fork but not mushy.
   Tip Draining the potatoes completely prevents the casserole from becoming watery.
2. 2Season the Potatoes and Ham
   Add the diced ham and seasonings to taste directly to the baking dish with the drained potatoes. Gently toss the ingredients together until the seasonings are evenly distributed throughout the mixture.
   Look for The ham and potatoes should be evenly mixed and coated in seasoning.
   Tip Tossing directly in the dish saves you from washing an extra mixing bowl.

At the end of this phase, the potatoes should be parboiled until they are just tender when pierced with a fork but still hold their shape without crumbling. Once drained and tossed in the baking dish with the savory diced ham and seasonings, the mixture should look colorful and be evenly distributed.

You should smell the mild aroma of seasonings combining with the savory scent of the ham, indicating that the base of your casserole is perfectly seasoned and ready for the sauce.

Sauce Making and Assembly

3. 3Pour the Sauce
   Pour the velvety béchamel sauce evenly over the seasoned potatoes and ham in the baking dish, ensuring it coats all the ingredients.
   Look for The sauce should coat the potatoes and ham smoothly without pooling excessively.
   Tip Gently tap the baking dish on the counter to help the sauce settle.
4. 4Top with Cheese
   Top the entire mixture with a generous, even layer of the shredded mozzarella cheese, spreading it to the edges of the dish.
   Look for The cheese should completely cover the potato and ham mixture.
   Tip Make sure the cheese reaches the very edges of the baking dish.

The velvety béchamel sauce should coat the potatoes and ham, seeping into all the crevices and filling the baking dish with a rich, creamy blanket. Once topped with the shredded mozzarella, the casserole should be completely covered in a white cheese layer, ready to be transformed by the heat of the oven into a golden masterpiece.

Baking to Golden Perfection

5. 5Bake until Golden and Bubbling
   Bake the casserole in the preheated oven at 375°F (190°C) for 25 to 30 minutes. Watch for the edges to bubble vigorously and the mozzarella cheese on top to blister into a beautiful golden brown color.
   Look for The cheese should be golden brown and bubbling actively around the sides.
   Tip If the cheese browns too quickly, tent the dish loosely with foil.
6. 6Rest and Serve
   Remove the baking dish from the oven and let it rest on the counter for 10 minutes. Serve hot, enjoying the massive, gooey cheese pull as you lift each rich, comforting portion from the dish.
   Look for The bubbling will subside, and the sauce will set slightly for clean slicing.
   Tip Resting prevents the creamy sauce from running when you cut into it.

At the end of the baking time, the casserole will be bubbling vigorously around the edges, and the mozzarella cheese on top will be beautifully melted, blistered, and golden brown. The aroma of baked cheese, rich cream, and savory ham will fill your entire kitchen. After resting on the counter, the bubbling will subside, and the sauce will set slightly, ensuring clean, neat portions with an epic, gooey cheese pull when served.

Common mistakes

One of the most common mistakes is skipping the parboiling step or undercooking the potatoes beforehand, which leads to hard, crunchy potato pieces in the finished dish. Another frequent error is using a watery ham, which can release excess liquid during baking and make the béchamel sauce runny.

Finally, do not bake the casserole uncovered the entire time if your oven runs hot, as the cheese might burn before the potatoes are heated through; tent with foil if the top browns too quickly.

How to tell it’s done

To determine if your casserole is perfectly baked, look for a deeply golden, blistered cheese topping and active bubbling around the edges of the dish. You can insert a paring knife or toothpick into the center of the casserole; it should slide into the potatoes with absolutely no resistance, confirming they are completely tender.

Since the ham is already fully cooked, you are simply heating the casserole through and melting the cheese, which takes about 25 to 30 minutes at 375°F (190°C).