- 6 potatoes, peeled and cut into 1/2-inch rounds
- 1 tablespoon olive oil
- 1 small onion, chopped
- 1 (10.75 ounce) can condensed cream of mushroom soup
- 1 cup grated Cheddar cheese
- 1 (5 ounce) can evaporated milk
- Preheat oven to 350 degrees F (175 degrees C).
- Place potatoes into a large pot and cover with salted water; bring to a boil. Reduce heat to medium-low and simmer until slightly tender, about 5 minutes. Drain.
- Heat olive oil in a skillet over medium heat; cook and stir onion until lightly browned and tender, 10 to 15 minutes.
- Mix onion, cream of mushroom soup, Cheddar cheese, and evaporated milk in a bowl. Arrange potatoes in a 9×13-inch casserole dish. Pour sauce over potatoes.
- Bake in the preheated oven until potatoes are tender and sauce is bubbling, 20 minutes.