Take traditional mashed potatoes to a whole new level. Cheesy French Onion Mashed Potato Casserole is incredibly rich and velvety smooth.
Enhance basic mashed potatoes with the addition of caramelized onions and garnish with a topping made of melty Gruyere cheese, kettle potato chips, and smoked paprika. This is a great side dish for a holiday dinner and can be served with many main courses.
Why you will love this loaded mashed potato casserole
- You can make this dish with your favorite mashed potato recipe. It is also a great way to use leftover mashed potatoes.
- Combine the mashed potatoes with butter, heavy cream, sour cream, garlic, and chives. Delicious flavor!
- Are you pressed for time when trying to pull together a holiday dinner? This is a great make-ahead recipe.
- While the caramelized onions take a little time to prepare, the resulting flavor is worth it. They partner well with the potatoes and the cheese.
- Make a topping with nutty gruyere cheese and crispy kettle potato chips. The cheesy crunchy topping adds great texture as a contrast to the creamy potatoes.
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What are Duchess Potatoes
This mashed potato recipe is based upon a classic French recipe, Duchess Potatoes. The potatoes are combined with butter, cream, and egg yolks. The potatoes are generally piped with a star tip into rosettes which are baked until the outside has browned on the edges.
Why add eggs to mashed potatoes?
Adding egg yolks to the mashed potatoes helps the recipe in a couple of ways.
- The egg yolks act as an emulsifier which helps to bind the ingredients together.
- The addition of egg yolks enhances the richness and creaminess of the potatoes.
What are the two types of potatoes?
Potatoes are classified by the texture of their interiors.
Waxy
Waxy potatoes have thin skin and dense and moist flesh. They are generally used in recipes that call for the potatoes to retain their shape after cooking such as potato salad. Red potatoes and fingerling are waxy varieties.
Mealy
Mealy or starchy potatoes have a fluffy and dry interior that falls apart after cooking. They are generally used for baked or mashed potatoes. Russet potatoes are a mealy variety.
Yukon Gold potatoes have properties of both types making them a good candidate for mashed potatoes.
Ingredients
Note - Pictured are red potatoes. The recipe is made with Yukon Gold potatoes which were not available when I took the photo.
Mashed Potatoes
Potatoes - Suggested varieties are Yukon gold or russet. Butter, garlic, heavy cream, sour cream, and chives are the flavor boosters. Egg yolks provide some richness and creaminess.
French Onions
Yellow onions provide sweetness with a touch of earthiness. Once the onions are caramelized, fresh thyme and white wine enhance and deepen their flavor. If you like French onion flavor, here is another potato recipe you may want to try - https://tenpoundcakecompany.com/french-onion-twice-baked-potatoes/
Topping
The casserole has a cheesy crunchy topping that delivers texture to the creamy mashed potatoes. Combine kettle potato chips with grated Gruyere cheese and smoked paprika.
Preparing the casserole
If you have leftover mashed potatoes, skip ahead to adding the sour cream and other ingredients. However, below is a recipe for mashed potatoes if needed. If you have a favorite recipe follow that one.
Mashed Potatoes
- Peel and cut potatoes into 1-2 inch pieces. Add 2-3 inches of water to a stock pot and place a steamer basket in the bottom of the pot over medium-high heat. Add the potatoes to the basket and bring the water to a slight boil. Make sure to have a lid on the pot.
- Steam the potatoes. They are cooked when fork tender. Remove the potatoes from the pot and drain the water. You can add the mashed potatoes back to the stockpot.
- Use a potato masher or ricer to mash the potatoes. Add the butter and the heavy cream. Mix thoroughly.
- Add the sour cream, garlic, chives, 1 teaspoon salt, and pepper to the potato mixture and incorporate.
- The potatoes may be a little cooler now. Add the egg yolks and stir until completely mixed.
- Add the potatoes to a buttered baking or casserole dish.
Caramelizing the onions
Prepare the onions while the potatoes are steaming. It takes 20-30 minutes to caramelize the onions.
- Cut the two large onions into thin strips, root to stem end.
- Add 2 tablespoons of olive oil to a skillet over medium heat. Add the sliced onions, kosher salt, and black pepper.
- Occasionally stir the onions so they do not stick to the bottom of the pan. You may see brown residue known as fond on the bottom of the pan.
- Add ¼ cup of water to deglaze the pan. Scrap the bottom of the pan to release the brown bits. Repeat this step in about 10 minutes.
- Once the deglazing is complete and the onions are sticking a little to the bottom of the pan, add the fresh thyme leaves and white wine to the pan for French onion flavor.
- Again scrape the bottom of the pan to release browned bits. Once the wine is absorbed, take the pan off the heat.
Assemble the casserole
Preheat the oven to 375 degrees.
Spread the onions over the top of the mashed potatoes in the baking dish. Create the topping by combining crushed potato chips with grated Gruyere cheese and smoked paprika.
Sprinkle the topping over the onions, completely covering them. Cover the dish with a sheet of aluminum foil. Coat the inside of the foil with cooking spray and cover the potatoes. Place the dish on a baking sheet and place in the oven. Bake for 50-55 minutes.
Substitutions
- You can use any cheese you prefer. I would stick with semi-hard cheeses for ease in shredding. Suggestions are parmesan or Swiss cheese.
- Add cream cheese as a replacement for sour cream. Use 8 ounces of cream cheese and an additional ¼ cup of heavy cream.
- If you prefer not to use white wine in the caramelized onions, use beef broth as a substitute. Add a dash of Worcestershire sauce for a flavor boost.
FAQ's
Cover the cooled baking dish with plastic wrap, and refrigerate. Reheat in a 350-degree oven until the center of the casserole is about 140 degrees.
Absolutely. Add the mashed potatoes to the baking dish and top with the caramelized onions. Cover the dish and refrigerate until you are ready to heat them. Add the cheesy and crunchy topping just before the potatoes go in the oven.
Yukon Gold potatoes are suggested as they have the best combination of properties from both waxy and mealy potatoes.
Cheesy Mashed Potatoes
This is a recipe that will become a family favorite. It combines the comfort of mashed potatoes with the savory richness of French onion soup.
This dish is a crowd pleaser - great for Sunday dinner or a holiday meal. Enjoy the creamy texture, the sweet caramelized onions, and the gooey melted cheese in every flavorful bite.
Recipe
Cheesy French Onion Mashed Potato Casserole
Equipment
- 1 casserole or baking dish
- 1 vegetable peeler
- 1 large pot
- 1 steamer basket or insert
- 1 cutting board
- 1 knife
- 1 medium skillet
- 1 small bowl
- 1 spoon or rubber spatula
- 1 potato ricer or masher
Ingredients
- 4 pounds Yukon Gold or russet potatoes (1.8 kilos)
- 2 tablespoons olive oil
- 2 yellow onions
- 5 sprigs fresh thyme
- ¼ cup white wine (4 ounces/118 ml)
- 1 stick unsalted butter (8 tablespoons/4 ounces/112 grams)
- 3 cloves garlic
- 8 ounces sour cream (227 grams)
- ½ cup heavy cream (4 ounces/118 ml)
- 4 tablespoons chives, minced
- 4 egg yolks
- 1½ cups grated Gruyere cheese (4 ounces/113 grams)
- 1½ cups kettle potato chips (2.5 ounces/70 grams)
- 1 teaspoon smoked paprika
- 1½ teaspoons kosher salt
- ½ teaspoon ground black pepper
Instructions
- This is a great recipe for leftover mashed potatoes. Following are the steps to make mashed potatoes for this recipe. However, use whatever method you prefer to make mashed potatoes. If you have leftover mashed potatoes skip to the step adding the sour cream and other ingredients.
Mashed Potatoes
- Peel and cut potatoes into 1-2 inch pieces. Add 2-3 inches of water to a stock pot. Place a steamer basket in the bottom of the pot and heat the water to a slight boil.
- Add the potatoes to the steamer basket and put a lid on the pot. Steam the potatoes until they are tender. The potatoes are cooked when a paring knife is easily inserted.
- Remove the potatoes from the stock pot and drain any remaining water. You can put the mashed potatoes back in the stock pot.
- Using a potato masher or ricer, mash the potatoes. Cut the butter into tablespoons and add one tablespoon at a time while mashing the potatoes.
- Add the heavy cream to the mashed potatoes and stir everything together to combine.
- Add the sour cream, chives, garlic, 1 teaspoon of salt, and ¼ teaspoon of black pepper to the potatoes. Stir to combine.
- The potatoes should be a little cooler now. Add the egg yolks to the mash and stir until they are completely incorporated.
- Add the mashed potatoes to a buttered casserole or baking dish. Smooth the top of the potatoes.
Caramelized Onions
- While the potatoes are steaming, caramelize the onions. Slice two onions into thin strips, root to stem end.
- Add 2 tablespoons of olive oil to a saute pan over medium heat. When hot, add the sliced onions. Season with ½ teaspoon of salt and ¼ teaspoon of ground black pepper.
- Stir the onions occasionally so they do not stick to the bottom of the pan. It is best to slowly caramelize the onions so they do not burn.
- After 15 minutes and as the onions cook, a liquid will be released which will leave a residue on the bottom of the pan. This residue is known as fond which will turn brown.
- Add ¼ cup of water to deglaze the pan. Scrap the bottom to release the fond. After 10 more minutes, repeat this step another time.
- Five minutes after the last deglazing, add the thyme leaves and ¼ cup of white wine. Scrap the bottom of the pan to release the fond. The onions should be a translucent very brown color.
Assembling the casserole
- Preheat the oven to 375°.
- Break the potato chips into small pieces. Add the grated Gruyere cheese and the smoked paprika to the potato chip pieces in a small bowl. Stir together to distribute the smoked paprika.
- Add the caramelized onions to the top of the mashed potatoes. Spread them to cover the entire surface of the potatoes.
- Add the potato chip/cheese mix to the top of the casserole, covering the surface of the onions.
- Cover the top of the casserole with aluminum foil. It helps to coat the inside surface of the foil with cooking spray so that the cheese doesn't stick to it as the casserole bakes.
- Bake for 45 minutes.
- Remove the foil from the casserole dish and place it back in the oven. Bake the mashed potato casserole for another 15 minutes.
- Let the casserole cool for 10-15 minutes before serving.
Notes
Substitutions
- You can use any cheese you prefer. I would stick with semi-hard cheeses for ease in shredding. Suggestions are parmesan or swiss cheese
- Add cream cheese as a replacement for sour cream. Use 8 ounces of cream cheese and an additional ¼ cup of heavy cream.
- If you prefer not to use white wine in the caramelized onions, use beef broth as a substitute. Add a dash of Worcestershire sauce for a flavor boost.
Nutrition
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