Sour Cream and Onion Potato Casserole

This crowd-pleasing side dish brings together two beloved flavors — creamy mashed potatoes and tangy sour cream and onion — to create a memorable holiday or weeknight addition to any menu. My Sour Cream and Onion Potato Bake is rich, easy to prepare, and finished with melted cheddar for a golden, savory top that guests will love.

Inspired by classic Southern casseroles, this version dresses up traditional mashed potatoes with caramelized onions, garlic, chives, and light sour cream for a bright, slightly tangy profile. It’s a versatile side that pairs well with roasted meats, holiday mains, and simple weeknight entrees. You can make it ahead, adapt it for dairy-free diets, and scale it easily to feed a crowd.

Ingredients

• 3 pounds russet potatoes, peeled and quartered
• 1 tablespoon plus 2 teaspoons kosher salt, divided
• 4 tablespoons salted butter, divided
• 2 cups thinly sliced yellow onion (about 1 medium onion)
• 3 garlic cloves, minced
• 1 cup light sour cream
• 1/2 cup freshly chopped chives, divided
• 1/4 cup low-sodium chicken broth (or vegetable broth)
• 2 teaspoons white wine vinegar
• 1/2 teaspoon freshly ground black pepper
• 1/2 cup shredded mild cheddar cheese

Step-by-step

Step one: Preheat the oven

Preheat the oven to 375°F (190°C).

Step two: Cook the potatoes

Place the peeled, quartered potatoes in a large pot and cover with cold water by about 2 inches. Bring to a boil, then add 1 tablespoon of kosher salt. Continue to boil until the potatoes are fork-tender, about 10 minutes depending on size.

Step three: Sauté the onions and garlic

While the potatoes cook, heat a large skillet over medium heat and melt 2 tablespoons of the butter. Add the sliced onions and minced garlic and cook, stirring occasionally, until the onions soften and become translucent, about 4 to 6 minutes. If you prefer deeper caramelization, cook a few minutes longer over medium-low heat. Remove from heat and set aside.

Step four: Drain and steam

When the potatoes are tender, drain them in a colander and allow steam to escape for about 5 minutes. This helps prevent watery mashed potatoes and yields a creamier texture.

Step five: Make them creamy

In a large mixing bowl combine the sour cream, chopped chives (reserve a small amount for garnish), chicken broth, white wine vinegar, black pepper, and the remaining 2 tablespoons of butter. Add the drained potatoes and mash to your preferred consistency — smooth or slightly chunky, according to taste.

Step six: Fold in the onion mixture

Stir the sautéed onions and garlic into the mashed potatoes. Taste and season with the remaining 2 teaspoons of kosher salt and additional pepper if needed. Mix gently to combine all flavors evenly.

Step seven: Bake the potatoes

Transfer the mashed potato mixture to an oven-safe 9×13-inch baking dish and spread into an even layer. Sprinkle the shredded mild cheddar cheese evenly over the top. Bake uncovered until the cheese is melted and lightly browned, about 10 to 15 minutes.

Step eight: Garnish and serve

Remove from the oven, sprinkle the remaining chives over the top, and serve hot. This Sour Cream and Onion Potato Bake is excellent alongside roasted turkey, chicken, pork, or as part of a holiday buffet.

Recipe FAQs

Additional info

• Author: Alex Snodgrass
• Servings: 8
• Prep time: 15 minutes
• Cook time: 30 minutes
• Total time: 45 minutes

If you try this Sour Cream and Onion Potato Bake, leave a comment with your tweaks or serving suggestions. It’s a simple, satisfying dish that elevates classic mashed potatoes into a tangy, cheesy crowd favorite — perfect for holidays, potlucks, and family dinners.