Pre-Summer Casserole: Just 4 ingredients. I assemble this early when I want a stress-free evening side dish.

This pre-summer casserole is what I throw together on those warm-ish evenings when I want something cozy but don’t want to babysit a pan on the stove. It’s just four ingredients, all tossed into one deep baking dish, then left alone in the oven until the top turns deeply roasted and umami-rich with caramelized corners. The idea came from my love of those crispy bits on the edge of a gratin or lasagna—this is basically a shortcut version that you can assemble ahead, stash in the fridge, and then bake off right before dinner for a totally stress-free side dish.

Serve this casserole alongside grilled chicken, pork chops, or simple baked fish—the savory, cheesy crust and tender potatoes love anything smoky or citrusy. I like to add a big green salad with a tangy vinaigrette or some steamed green beans to balance the richness. If you’re keeping it casual, it’s also great with burgers or sausages from the grill, plus a crunchy slaw. Leftovers reheat nicely with a fried egg on top for an easy brunch situation.

Servings: 6

2 pounds small yellow potatoes, thinly sliced (about 1/8-inch thick)

Preheat your oven to 400°F (200°C). Lightly grease a deep 8x8-inch or similar baking dish with a little oil or nonstick spray for easier cleanup.

In a large bowl, toss the thinly sliced potatoes with the condensed cream of mushroom soup until every slice is lightly coated. The soup should act like a thick, savory sauce—no extra liquid needed.

Spread half of the potato mixture evenly into the prepared baking dish, pressing it gently into an even layer so it cooks uniformly.

Sprinkle 3/4 cup of the shredded sharp cheddar cheese evenly over this first layer of potatoes.

Add the remaining potato mixture on top, smoothing it out into an even layer and making sure the potatoes are tucked down into the sauce so they soften as they bake.

In a small bowl, combine the remaining 3/4 cup shredded sharp cheddar cheese with the 1/2 cup grated Parmesan cheese, tossing them together. Sprinkle this cheese mixture evenly over the top of the potatoes to form a thick, even layer—this is your umami-rich crust.

Cover the baking dish tightly with foil and bake in the preheated oven for 35 minutes, until the potatoes are starting to turn tender and the casserole is bubbling around the edges.

Remove the foil and return the dish to the oven. Continue baking uncovered for 25 to 35 minutes, or until the top is deeply golden-brown with crispy, caramelized edges and the potatoes are very tender when pierced with a knife.

For an extra roasted, almost crunchy crust, switch the oven to broil for 2 to 4 minutes at the very end, watching closely so the cheese darkens in spots without burning.

Let the casserole rest for at least 10 minutes before serving. This short rest helps the layers set up a bit and makes it easier to scoop out neat, cheesy squares with those irresistible caramelized corners.

To keep this truly four ingredients, everything is built around pantry basics, but you can still tweak the flavor. For extra umami, swap half of the sharp cheddar for smoked cheddar or Gruyère, or use a roasted garlic or roasted mushroom condensed soup if you can find it. If you want to stretch the casserole into more of a main dish while still honoring the spirit of the recipe, you can serve it topped with rotisserie chicken or seared sausage slices instead of baking them in. For make-ahead prep, you can assemble the entire dish earlier in the day, cover tightly, and refrigerate for up to 8 hours; when baking from cold, add 5 to 10 extra minutes to the covered bake time before removing the foil. Food safety notes: Keep the casserole refrigerated until you’re ready to bake, and don’t leave it at room temperature for more than 2 hours once cooked. If you slice the potatoes in advance, store them fully submerged in cold water in the fridge and drain/dry well before mixing with the soup so the sauce doesn’t get watery. Leftovers should be cooled quickly, stored in an airtight container in the refrigerator, and eaten within 3 to 4 days, reheating until steaming hot all the way through.