Sour Cream & Onion Potato Casserole
Published: Friday, May 29, 2026
3 lb. russet potatoes, peeled and quartered
1 tsp. olive oil
2 c. chopped onions
3 cloves garlic, minced
1 Tbsp. sugar
1 Tbsp. white vinegar
1½ c. sour cream
1 c. buttermilk
¼ c. salted butter
1½ tsp. salt
½ tsp. freshly ground black pepper
4 green onions, chopped
1 bunch green chives, chopped, plus more for garnish
½ c. shredded white Cheddar cheese
½ c. coarsely crushed sour cream and onion potato chips
Preheat oven to 375°. Place potatoes in a 6- to 8-qt. pot; cover with salted water. Bring to a boil over high heat, then reduce heat to medium and simmer for 25 minutes, or until very tender.
Meanwhile, heat olive oil in a large skillet over medium heat. Add onions, garlic, sugar and vinegar and cook mixture, stirring occasionally, until onions are tender and caramelized, adding water 1 Tbsp. at a time, as needed, to prevent sticking, about 20 minutes; set aside.
Once potatoes are cooked, drain and return to the pot. Turn heat to high; cook and stir potatoes for 30 seconds to help remove extra cooking liquid from potatoes. Remove from heat and add sour cream, buttermilk, butter, salt and pepper. Mash with a potato masher until smooth and fluffy. Add cooked onion mixture, green onions and chives to the potato mixture; stir to combine.
Spread in a 2-qt. baking dish. Sprinkle with cheese and potato chips. Bake until cheese is melted, about 20 minutes. Garnish with additional chopped fresh chives. —8 servings.
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