This oven baked 3-ingredient tomato soup potato casserole is exactly the kind of recipe I lean on when life is busy but I still want something cozy on the table. My neighbor brought a pan of this to a backyard potluck a few summers ago, and it disappeared before the burgers did. Everyone circled back to her asking how she made it, and we were all shocked when she said, “Just potatoes, canned tomato soup, and butter.” The thin-sliced potatoes soak up the creamy tomato soup, the edges get a little browned and sticky, and the whole thing tastes like a cross between scalloped potatoes and tomato soup—using ingredients most of us already have in the pantry.
Serve this casserole as a comforting side dish with roasted or grilled chicken, meatloaf, or pork chops. It’s also great next to simple baked fish or a green salad if you want to keep things lighter. I like to add something crisp and fresh on the side—like steamed green beans, roasted broccoli, or a crunchy coleslaw—to balance the rich, buttery potatoes. Leftovers reheat well and make an easy lunch alongside a fried egg or a small side of cottage cheese.
Oven Baked 3-Ingredient Tomato Soup Potato CasseroleServings: 6
Ingredients
2.5 to 3 pounds russet or Yukon Gold potatoes, peeled and thinly sliced (about 1/8 inch thick)
2 (10.5-ounce) cans condensed tomato soup (undiluted, straight from the can)
6 tablespoons unsalted butter, melted, plus a little extra for greasing the dish
Directions
Preheat your oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish with a bit of butter to keep the potatoes from sticking.
Peel the potatoes and slice them as evenly and thinly as you can, about 1/8 inch thick. A sharp knife works fine; a mandoline makes this go even faster if you have one. Try to keep the slices similar in thickness so they cook evenly.
In a medium bowl, whisk the condensed tomato soup until smooth. It should be thick but pourable straight from the can—do not add water or milk, since you want a rich, thick sauce that will cling to the potatoes.
Spoon a thin layer of tomato soup (about 1/4 cup) into the bottom of the greased baking dish and spread it around to lightly coat the bottom. This helps keep the first layer of potatoes from sticking.
Arrange a layer of potato slices over the bottom of the dish, slightly overlapping them like shingles. It doesn’t need to be perfect, just try to cover the bottom in a mostly even layer.
Drizzle a little melted butter over the potatoes (about 2 tablespoons), then spoon or pour some of the tomato soup over the top (about 1/3 of what’s left), spreading it gently with the back of a spoon so it coats most of the potatoes.
Repeat the layers: potatoes, melted butter, and tomato soup, until you’ve used all of the potatoes and soup. Finish with a generous layer of tomato soup on top so the surface is mostly covered. Drizzle any remaining melted butter over the top.
Cover the baking dish tightly with aluminum foil. Bake in the preheated oven for 45 minutes. This covered time helps the potatoes steam and get tender in the tomato sauce.
After 45 minutes, carefully remove the foil (watch for steam). Continue baking uncovered for another 25 to 35 minutes, or until the potatoes are very tender when pierced with a knife and the top is thickened, bubbly, and browned around the edges. Total baking time will be about 1 hour 10 minutes to 1 hour 20 minutes, depending on how thinly the potatoes were sliced.
Once done, remove the casserole from the oven and let it rest for at least 10 to 15 minutes before serving. This short rest helps the sauce thicken up a bit more so the slices hold together better when scooped. Serve warm straight from the baking dish.
Variations & Tips
To keep this true to its 3-ingredient charm, the base recipe uses only potatoes, condensed tomato soup, and butter, but you can still tweak it slightly to fit your taste and schedule. If you want a little extra richness, you can swap half of the melted butter for olive oil, or dot small pieces of butter between the layers instead of melting it first. For a creamier texture, stir a splash of heavy cream into the tomato soup before layering (this technically adds a fourth ingredient, but it stays close to the original idea). If you like a bit of tang, you can whisk a spoonful of sour cream into the soup as well. To make prep faster on a weeknight, slice the potatoes in the morning, keep them submerged in cold water in the fridge to prevent browning, then drain and pat dry before assembling and baking at dinnertime. You can also assemble the whole casserole several hours ahead, cover, and refrigerate; add 10 to 15 minutes to the baking time if you’re starting from cold. For a slightly crispier top, move the casserole to the top rack for the last 5 minutes of baking, or broil briefly while watching closely so it doesn’t burn. Food safety tips: Always refrigerate leftovers within 2 hours of baking. Store the cooled casserole tightly covered in the refrigerator and use within 3 to 4 days. Reheat individual portions in the microwave until steaming hot in the center, or rewarm the whole dish in a 325°F oven, covered, until heated through. If you prepare this ahead, keep the sliced potatoes chilled until baking and do not leave the assembled uncooked casserole at room temperature for extended periods to reduce the risk of bacterial growth.
