This oven baked 4-ingredient tuna and potato casserole is one of those cozy, old-fashioned dishes that takes me right back to Sunday suppers at my aunt’s house. She’d slide this bubbling, golden pan out of the oven and the whole kitchen would smell like comfort. I love that it uses just a few pantry basics—canned tuna, potatoes, cream of mushroom soup, and cheese—yet it still tastes like something special. It’s the kind of practical, no-fuss recipe you can throw together on a busy weeknight, but it still has that vintage family-favorite feel that makes everyone linger around the table a little longer.
Serve this casserole hot, straight from the oven, with a simple green salad or steamed green beans to balance the richness. Buttered peas or corn are kid-friendly sides that go over well, too. A basket of warm dinner rolls or crusty bread is perfect for soaking up the creamy sauce from the bottom of the dish. If you’d like to stretch the meal a bit further, add a bowl of fruit salad or sliced apples on the side for something light and fresh.
Oven Baked 4-Ingredient Tuna and Potato CasseroleServings: 6
Ingredients
4 cups thinly sliced peeled potatoes (about 4 medium russet or Yukon Gold potatoes)
2 (10.5 oz) cans condensed cream of mushroom soup
2 (5 oz) cans tuna in water, drained and flaked
2 cups shredded cheddar cheese, divided
Directions
Preheat your oven to 375°F (190°C). Lightly grease a 9x13-inch glass baking dish so the potatoes don’t stick.
Peel the potatoes and slice them thinly, about 1/8 inch thick. The thinner they are, the more tender they’ll get and the creamier the casserole will be.
In a medium bowl, stir together the condensed cream of mushroom soup and 1/2 cup of water until smooth. This thins the soup just enough to coat the potatoes and tuna while still baking up nice and creamy.
Spread a thin layer (about 1/3) of the soup mixture over the bottom of the prepared baking dish. This helps keep the bottom potatoes from sticking and drying out.
Arrange half of the sliced potatoes in an even layer over the soup in the baking dish, overlapping the slices slightly like shingles.
Scatter half of the drained, flaked tuna evenly over the potato layer, breaking up any larger chunks with your fingers as you go.
Sprinkle 3/4 cup of the shredded cheddar cheese over the tuna and potatoes.
Spoon and spread another 1/3 of the soup mixture over the cheese layer, making sure to cover as much of the surface as you can.
Repeat the layers with the remaining potatoes and tuna: arrange the rest of the potatoes in an even layer, then scatter the remaining tuna over the top.
Pour and spread the remaining soup mixture evenly over the top layer, letting it drip down between the potatoes a bit. Gently tap the dish on the counter to help the sauce settle.
Cover the baking dish tightly with foil and bake in the preheated oven for 45 minutes. This steams the potatoes so they turn tender and soak up the creamy sauce.
Carefully remove the foil, then sprinkle the remaining 1 1/4 cups shredded cheddar cheese evenly over the top of the casserole.
Return the uncovered casserole to the oven and bake for another 20–25 minutes, or until the cheese is melted, bubbling, and lightly golden and the potatoes are very tender when pierced with a fork.
If you’d like a deeper golden top, you can broil the casserole on high for 1–2 minutes at the end, watching closely so the cheese doesn’t burn.
Let the casserole rest for 10–15 minutes before serving. This helps the creamy sauce thicken slightly and makes it easier to scoop neat portions. Serve warm right from the glass baking dish.
Variations & Tips
For picky eaters, use mild cheddar or a blend of cheddar and mozzarella so the flavor is softer, and cut the tuna a bit smaller so it’s less noticeable in each bite. If your family loves extra creaminess, stir an additional half can of cream of mushroom soup into the sauce mixture (still counting as the same ingredient) or use a thicker cut of potatoes for a heartier bite. You can also swap cheddar for Monterey Jack or Colby if that’s what you have on hand. For a little more flavor without adding new ingredients, season the potatoes lightly with salt and pepper as you layer, or use a sharp cheddar for a more pronounced cheesy taste. To make this casserole ahead, assemble it up to the point of baking, cover tightly, and refrigerate for up to 24 hours; when you’re ready, bake it covered, adding 5–10 extra minutes to account for the chill. Leftovers reheat nicely in the oven, covered with foil, at 350°F until warmed through, and they’re great for next-day lunches. If someone in your house is unsure about tuna, try making half the pan with extra cheese and fewer tuna flakes on that side so they can ease into it without feeling overwhelmed.
