My frugal aunt always made this rich 4-ingredient comfort dish when money was tight in the spring. It turns the humblest pantry staples into a creamy decadent masterpiece that everyone begs for.

When I was a girl on our little Midwestern farm, my frugal aunt Ruth had a way of turning the lean months of early spring into something that still felt like Sunday supper. The pantry might have held nothing more than a sack of potatoes, a bit of onion, some flour, and a jar of milk, but she’d layer it all into a slow cooker and let it bubble away into the richest, creamiest scalloped potatoes you could imagine. This four-ingredient version is bare-bones simple and budget-friendly, but it bakes up into a thick, velvety sauce with tender potato slices and a golden, caramelized edge that tastes like pure comfort. It’s the kind of humble, stick-to-your-ribs dish you make when money is tight but you still want the table to feel special.

These slow cooker scalloped potatoes are hearty enough to be the star of a simple supper with just a green salad or steamed peas alongside. They’re wonderful next to baked ham, meatloaf, or roasted chicken, and they soak up gravy or pan drippings like a dream. For a meatless plate, serve them with buttered green beans and sliced tomatoes when they’re in season. A basket of warm bread or biscuits never hurts either, especially for swiping up every last bit of that creamy sauce.

Servings: 6

3 pounds russet or Yukon Gold potatoes, very thinly sliced

Lightly grease the inside of a 4- to 6-quart slow cooker with butter to help keep the potatoes from sticking and to encourage a light golden edge.

Peel the potatoes if you like a smoother look, or simply scrub them well and leave the skins on for a more rustic dish. Slice the potatoes very thinly, about 1/8 inch thick, so they become tender and creamy as they cook.

Peel and thinly slice the onion into half-moons. The onion will soften and almost melt into the sauce, giving the potatoes that old-fashioned, cozy flavor Aunt Ruth always loved.

In a small bowl, stir together the flour, salt, and pepper (if using). This seasoned flour is the secret to turning simple milk into a thick, rich cream sauce without any fancy ingredients.

Spread a thin, even layer of potato slices over the bottom of the slow cooker. Scatter a small handful of onion slices over the potatoes.

Sprinkle a tablespoon or two of the flour mixture evenly over the potatoes and onions. This helps the sauce thicken between the layers as it cooks.

Repeat the layers: potatoes, onions, then a light dusting of the flour mixture, until you’ve used all the potatoes and onions, finishing with a layer of potatoes on top.

Slowly pour the milk over the layered potatoes and onions, trying to moisten all the layers. Gently press down on the potatoes with the back of a spoon to settle them into the milk so everything is just about covered.

Cover the slow cooker with the lid and cook on HIGH for 3 1/2 to 4 1/2 hours, or on LOW for 6 to 7 hours, until the potatoes are very tender when pierced with a fork and the milk and flour have thickened into a creamy sauce.

For a golden brown crust like the old oven-baked casseroles, carefully remove the ceramic insert from the slow cooker (if it’s oven-safe) when the potatoes are done. Place it, uncovered, under a preheated broiler for 3 to 6 minutes, watching closely, until the top is bubbly and browned around the edges.

Let the scalloped potatoes rest for about 10 to 15 minutes before serving. This short rest helps the sauce thicken further so each spoonful holds together in rich, creamy layers on the plate.

If your pantry allows, a little extra richness goes a long way: you can swap 1 cup of the milk for evaporated milk or light cream for an even silkier sauce. For a cheese-topped version, sprinkle 1 to 1 1/2 cups shredded cheddar or Colby over the top during the last 20 to 30 minutes of slow cooking, or just before broiling. To stretch the dish when feeding a crowd, add another pound of potatoes and a splash more milk, then season a bit more generously. For added flavor without extra cost, stir 1 teaspoon of dried thyme or parsley into the flour mixture, or tuck a clove of garlic, finely minced, into the layers with the onions. If you prefer a firmer, sliceable casserole, cook on LOW and be sure to let it rest the full 15 minutes before serving. Leftovers reheat well in a skillet with a splash of milk, and they make a fine base for a simple hash with bits of leftover ham or sausage stirred in.