My grandmother made this every Sunday when money was tight. Three ingredients and feeds the whole family.

This oven baked 3-ingredient poor man's potato casserole is the kind of recipe my grandmother leaned on every Sunday when money was tight but the house was full. It’s made with just potatoes, milk, and a little butter, yet it turns into the coziest, creamy layered casserole with a golden brown top. No fancy ingredients, no complicated steps—just simple, pantry-staple comfort food that stretches a bag of potatoes to feed the whole family. It’s perfect for busy weeks when you want something warm and filling in the oven while you catch up on laundry, homework checks, or just finally sit down for a minute.

Serve this casserole hot, straight from the oven, with a simple green salad or steamed frozen veggies to round things out. It also pairs really well with roasted or pan-fried sausage, baked chicken thighs, or even just fried eggs on top if you’re keeping it extra budget-friendly. Leftovers reheat nicely in the microwave or oven and make a great base for the next day’s dinner—add a scoop of beans, a little leftover meat, or some sautéed onions on the side to turn it into a full meal without much extra work.

Servings: 6-8

3 pounds russet or Yukon Gold potatoes, thinly sliced

Preheat your oven to 375°F (190°C). Lightly grease a 9x13-inch glass casserole dish with a little butter so the potatoes don’t stick.

Wash and peel the potatoes (you can leave the skins on if you like a more rustic feel). Using a sharp knife or mandoline, slice the potatoes as thinly and evenly as you can, about 1/8 inch thick. The thinner the slices, the creamier the casserole.

In a small saucepan or microwave-safe bowl, gently warm the milk with the 4 tablespoons of butter until the butter is melted. You don’t need it boiling, just warm. Stir in the salt and black pepper, if using.

Arrange a snug, even layer of potato slices in the bottom of the prepared casserole dish, overlapping them slightly like shingles. Pour a little of the warm milk-butter mixture over the top, just enough to lightly coat the potatoes.

Continue layering: add another layer of potatoes, then more of the milk-butter mixture. Repeat until you’ve used all the potatoes, finishing with a layer of potatoes on top. Pour any remaining milk-butter mixture evenly over the top so the liquid comes almost to the top layer but doesn’t completely submerge it. Gently press down on the potatoes with your hands or the back of a spoon to help them settle.

Cover the casserole dish tightly with foil. Bake in the preheated oven for 45 minutes, until the potatoes are starting to turn tender when pierced with a knife.

Remove the foil and continue baking for another 25–35 minutes, or until the top is golden brown, the milk has thickened into a creamy sauce, and the potatoes are very tender all the way through. If the top is browning too quickly, you can loosely re-cover with foil.

Let the casserole rest for at least 10–15 minutes before serving. This helps the layers set up so it scoops out more neatly and the sauce thickens a bit more. Serve warm, straight from the glass dish, with big spoonfuls for everyone around the table.

To keep the spirit of the original tight-budget, three-ingredient casserole, think of add-ins as optional extras for weeks when you have a little more wiggle room. For more richness, swap part of the milk for a splash of cream or evaporated milk. If you have cheese on hand, sprinkle a small handful between the layers or over the top for a gratin-style twist. A sliced onion layered with the potatoes adds sweetness and depth, and a clove or two of minced garlic stirred into the milk-butter mixture brings extra flavor without much cost. You can also mix in a pinch of dried herbs like thyme or parsley when you’re not strictly counting ingredients. For meal prep, assemble the casserole earlier in the day, cover, and refrigerate; when you get home from work, pop it straight into the oven and just add 10–15 minutes to the baking time. Leftovers can be cooled, sliced into squares, and stored in airtight containers in the fridge for up to 3 days—reheat in the oven or air fryer to crisp the top back up, or in the microwave for a quick, no-fuss side.