This oven baked 3-ingredient mushroom soup potato casserole is exactly the kind of dish that quietly shows up at a holiday like Easter and suddenly steals all the attention. My sister-in-law made a version of this a few years ago, and everyone kept going back for “just one more scoop” until the pan was scraped clean. It’s fork-tender, super rich, and ridiculously simple—just potatoes, canned cream of mushroom soup, and butter. No chopping onions, no making a roux, nothing fancy. It’s the perfect busy-weeknight or bring-to-the-family-dinner recipe because you toss it together in minutes, let the oven do the work, and pull out a bubbling, creamy casserole that looks and smells like you spent way more time on it than you actually did.
This casserole is a natural side for ham, roast chicken, or pork tenderloin, especially for holiday dinners or Sunday suppers. I like to balance its richness with something fresh and bright, like a simple green salad with a tangy vinaigrette or steamed green beans with lemon. If you’re turning it into a cozy weeknight meal, pair it with rotisserie chicken and a bagged salad to keep things easy. It also works great alongside grilled sausages or a hearty veggie main, and any leftovers reheat well next to scrambled eggs for a very comforting breakfast-for-dinner situation.
Oven Baked 3-Ingredient Mushroom Soup Potato CasseroleServings: 8
Ingredients
3 pounds russet or Yukon Gold potatoes, peeled and thinly sliced (about 1/8–1/4 inch thick)
2 (10.5-ounce) cans condensed cream of mushroom soup
1/2 cup (1 stick) unsalted butter, melted, plus a little extra for greasing the dish
1/2 cup water or milk (optional but recommended for thinning the soup slightly; does not count as an ingredient)
1 teaspoon kosher salt (or to taste; optional)
1/2 teaspoon black pepper (optional)
Directions
Preheat your oven to 350°F (175°C). Lightly grease a 9x13-inch baking dish with a bit of butter so the potatoes don’t stick.
Peel the potatoes and slice them into thin rounds, about 1/8–1/4 inch thick. Try to keep the slices roughly the same thickness so they cook evenly. If you’re moving slowly, you can keep the sliced potatoes in a bowl of cold water to prevent browning, then drain and pat dry before layering.
In a medium bowl, whisk together the condensed cream of mushroom soup and the melted butter until smooth and combined. If the mixture feels very thick, whisk in the water or milk to loosen it slightly so it’s more pourable. Season with salt and pepper if you’d like, keeping in mind that the soup already has some salt.
Layer about half of the sliced potatoes evenly in the bottom of the prepared baking dish, overlapping them slightly like shingles. Pour or spoon about half of the mushroom soup–butter mixture over the potatoes, spreading it gently with a spatula to cover as much as you can.
Add the remaining potatoes on top in an even layer, then pour the rest of the mushroom soup–butter mixture over the top. Use the back of a spoon or spatula to nudge the sauce down between some of the potato layers so everything gets coated. The sauce will bubble up and spread more as it bakes.
Cover the baking dish tightly with aluminum foil. Bake for 60 minutes, then carefully remove the foil (watch for steam). The potatoes should be starting to soften and the sauce will be hot and bubbly around the edges.
Return the uncovered casserole to the oven and bake for another 25–35 minutes, or until the top is lightly golden, the sauce is bubbling all over, and the potatoes are fork-tender when you poke the center with a knife or fork. Total bake time is usually 1 hour 30 minutes, depending on how thick your potatoes are sliced and your oven.
Once done, remove the casserole from the oven and let it rest for at least 10–15 minutes before serving. This short rest lets the sauce thicken slightly so it’s creamy instead of runny when you scoop it out. Serve warm, straight from the baking dish, with big spoonfuls of the bubbling, creamy potatoes in a large serving bowl.
Variations & Tips
To keep the spirit of a 3-ingredient showstopper, try swapping just one element at a time. For a different flavor, use cream of celery or cream of chicken soup instead of mushroom. If you like a little extra richness, drizzle an additional 2–3 tablespoons of melted butter over the top before baking. For a slightly lighter version, thin the soup with low-sodium chicken broth instead of milk and use 6 tablespoons of butter instead of a full stick. You can also change up the potatoes: Yukon Golds make the casserole extra creamy, while russets give a softer, almost mashed-potato texture. If you want more color and texture without much effort, sprinkle a handful of shredded cheese over the top during the last 10–15 minutes of baking, or finish with chopped fresh parsley or chives right before serving. To prep ahead, assemble the casserole up to the point of baking, cover tightly, and refrigerate for up to 24 hours; add 10–15 minutes to the covered bake time since it will be starting cold. Leftovers reheat well in the oven, covered with foil at 325°F until warmed through, or in the microwave in short bursts, and they thicken up even more by the next day.
