I created a Classic Comfort Food casserole that layers tender sliced potatoes with French onion soup flavors, melted cheese and a crown of crispy fried onions ready for family dinners and potlucks.

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I love when a simple idea turns into something people actually fight over at the table. My Easy French Onion Potato Bake starts with thinly sliced Yukon Gold potatoes and ends under a melty layer of Gruyere that browns just right.

I stack it like a Layered Potatoes Bake so each forkful has soft potato, creamy bits and a crunchy finish, it feels a little like a Cheese Potatoes Casserole but with a savory twist that makes folks ask for the recipe. I don’t mean to be dramatic but sometimes dinner becomes the whole night.

Ingredients

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Potatoes provide carbs and fiber, earthy flavor, make this bake hearty and filling
Yellow onions add sweet savory depth when caramelized modest vitamins and antioxidants
Gruyere or Swiss offers melty nutty flavor, adds protein and calcium, makes it rich
Sour cream lends tangy creaminess contributes fat and calories and balances sweet onions
Condensed French onion soup packs salty umami and onion punch, boosts savory depth and seasoning
French fried onions give crunchy topping and texture, mostly carbs and fat from frying
Butter garlic thyme: butter enriches, garlic gives sharpness, thyme adds herbaceous brightness

Ingredient Quantities

2 1/2 to 3 pounds potatoes thinly sliced (Yukon Gold or Russet)

3 large yellow onions thinly sliced

2 cloves garlic minced

3 tablespoons unsalted butter divided

1 tablespoon olive oil

1 (10.5 ounce) can condensed French onion soup

1 cup sour cream

1/2 cup milk

1 teaspoon Worcestershire sauce optional

1 teaspoon fresh thyme leaves or 1/2 teaspoon dried thyme

2 cups shredded Gruyere or Swiss cheese

1 cup French fried onions plus extra for sprinkling

Salt and black pepper to taste

How to Make this

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1. Preheat oven to 375 F (190 C). Grease a 9×13 inch baking dish with 1 tablespoon butter or oil so potatoes won’t stick.

2. Thinly slice 2 1/2 to 3 pounds potatoes about 1/8 inch thick (mandoline is great if you have one, be careful). Pat slices dry with paper towels so they layer neatly.

3. Melt 2 tablespoons butter with 1 tablespoon olive oil in a large skillet over medium-low heat. Add 3 large thinly sliced yellow onions and a pinch of salt, cook slowly 20 to 25 minutes until deeply golden and soft, stirring every few minutes so they don’t burn. Add 2 minced garlic cloves in the last 1 to 2 minutes and stir.

4. In a bowl whisk together 1 (
10.5 oz) can condensed French onion soup, 1 cup sour cream, 1/2 cup milk, 1 teaspoon Worcestershire sauce if using, and 1 teaspoon fresh thyme leaves (or 1/2 teaspoon dried). Taste and season with salt and black pepper. Stir about half the caramelized onions into this mixture.

5. Arrange a single layer of potato slices in the prepared dish, overlap slightly. Season lightly with salt and pepper. Spoon about a third of the soup/onion sauce over the potatoes, then sprinkle about one third of the shredded Gruyere or Swiss cheese. Repeat to make another layer.

6. Finish with the remaining potato slices on top, pour the rest of the sauce evenly over everything so it seeps between layers. Press gently to compact a bit. Dot with the remaining 1 tablespoon butter if you like extra browning.

7. Cover the dish tightly with foil and bake 45 to 55 minutes, or until a knife or fork easily pierces the potatoes. If potatoes were sliced very thin you might need less time, check at 40 minutes.

8. Remove foil, sprinkle the remaining cheese over the top and spread 1 cup French fried onions evenly. Return to oven uncovered for 10 to 15 minutes until cheese is melted and edges are bubbly and onions are crisp and golden.

9. Let the casserole rest 10 minutes before serving so it sets up. Sprinkle extra French fried onions on top just before serving for extra crunch. Serve warm.

Equipment Needed

1. 9×13 inch baking dish (greased with butter or oil)
2. Mandoline slicer or a very sharp chef’s knife plus a cutting board — be careful with fingers
3. Large skillet (10 to 12 inch) for slowly caramelizing the onions
4. Mixing bowl and whisk to combine the soup, sour cream and milk
5. Measuring cups and spoons for accuracy
6. Cheese grater for the Gruyere or Swiss
7. Spatula or wooden spoon for stirring and spreading
8. Aluminum foil and oven mitts for safe baking and covering the dish
9. Paper towels or a clean kitchen towel to dry the potato slices
10. Can opener and a small paring knife for garlic and can prep

FAQ

Q: Can I use other kinds of potatoes? A: Yes, go ahead. Yukon Golds hold their shape and give a creamier texture while Russets get fluffier and absorb more sauce, slice them about 1/8 inch thick so they cook evenly, thicker slices need more time.

Q: Can I make it ahead of time? A: Totally, you can assemble, cover and refrigerate up to 24 hours, bake straight from fridge but add 10 to 15 minutes to the bake time; you can also freeze an assembled pan for up to a month, thaw overnight in fridge then bake longer.

Q: How do I get a crispy top and not a soggy middle? A: Add most of the French fried onions at the very end or sprinkle some on before broiling for 1 to 2 minutes, make sure potato slices are thin and evenly layered and don't overload with liquid, also partially cook onions until golden for better flavor.

Q: Can I make this dairy free or lower fat? A: Yes replace sour cream with plain dairy free yogurt or silken tofu blended, use plant milk and vegan cheese but expect less browning and a slightly different texture, using low fat sour cream and milk works too but it's less rich.

Q: Want to add meat or veggies, is that ok? A: Sure, add cooked bacon, ham or caramelized mushrooms and spinach, just cook them first so they dont release too much moisture while baking, avoid adding raw meat.

Q: How do I store and reheat leftovers? A: Keep in fridge 3 to 4 days in a covered dish, reheat covered at 350 F until hot about 20 to 30 minutes for a whole pan, single portions microwave fine, to re-crisp top broil briefly for a minute or two.

Easy French Onion Potato Bake Recipe Substitutions and Variations

Potatoes: swap Yukon Gold or Russet for red potatoes or fingerlings if you want a waxier, firmer bite that holds its shape. If you try sweet potatoes know they’ll be sweeter and softer so slice a little thinner and cut milk by about 2 tablespoons.
Yellow onions: use leeks or shallots instead. Leeks give a milder, buttery flavor (clean them well), shallots caramelize quicker and add a sweeter, more delicate onion note.
Condensed French onion soup: make a quick substitute with 1 cup beef broth + 2 tsp Worcestershire + 1 tsp soy sauce + 1/4 cup finely chopped caramelized onions; stir in 1 tsp cornstarch if you need it thicker. You get the same savory, umami punch without the canned soup.
Gruyere or Swiss cheese: swap for sharp cheddar or fontina for good melt and more bite, or use Monterey Jack for a milder, gooey top. For extra nuttiness add about 1/4 cup grated Parmesan mixed in.

Pro Tips

– Make your potato slices the same thickness, or you’ll get some pieces mushy and some still firm. A mandoline helps, but use the hand guard or a cut-resistant glove, and pat the slices very dry so the casserole doesn’t turn out watery.

– Taste the sauce before you salt. Canned French onion soup and the cheese already have a lot of salt, so either use a low-sodium soup or hold off on adding extra until you’ve mixed everything and tasted. Too salty at the start is hard to fix later.

– Take your time with the onions. Cook them low and slow until they’re deep golden for the best flavor, and only add the garlic at the end so it doesn’t burn. It’s a bit boring to wait but the payoff is huge.

– Keep the crispy onions crispy by adding most of them at the very end, or toast some separately on a sheet pan so they stay crunchy. If you want extra browning on the cheese, broil for just a minute or two but watch it the whole time, it’ll go from perfect to burnt fast.

Easy French Onion Potato Bake Recipe

Recipe by Sarah level

0.0 from 0 votes

I created a Classic Comfort Food casserole that layers tender sliced potatoes with French onion soup flavors, melted cheese and a crown of crispy fried onions ready for family dinners and potlucks.

Servings

servings

Calories

434

kcal

Equipment: 1. 9×13 inch baking dish (greased with butter or oil)
2. Mandoline slicer or a very sharp chef’s knife plus a cutting board — be careful with fingers
3. Large skillet (10 to 12 inch) for slowly caramelizing the onions
4. Mixing bowl and whisk to combine the soup, sour cream and milk
5. Measuring cups and spoons for accuracy
6. Cheese grater for the Gruyere or Swiss
7. Spatula or wooden spoon for stirring and spreading
8. Aluminum foil and oven mitts for safe baking and covering the dish
9. Paper towels or a clean kitchen towel to dry the potato slices
10. Can opener and a small paring knife for garlic and can prep

Ingredients

2 1/2 to 3 pounds potatoes thinly sliced (Yukon Gold or Russet)
3 large yellow onions thinly sliced
2 cloves garlic minced
3 tablespoons unsalted butter divided
1 tablespoon olive oil
1 (10.5 ounce) can condensed French onion soup
1 cup sour cream
1/2 cup milk
1 teaspoon Worcestershire sauce optional
1 teaspoon fresh thyme leaves or 1/2 teaspoon dried thyme
2 cups shredded Gruyere or Swiss cheese
1 cup French fried onions plus extra for sprinkling
Salt and black pepper to taste

Directions

Preheat oven to 375 F (190 C). Grease a 9×13 inch baking dish with 1 tablespoon butter or oil so potatoes won't stick.
Thinly slice 2 1/2 to 3 pounds potatoes about 1/8 inch thick (mandoline is great if you have one, be careful). Pat slices dry with paper towels so they layer neatly.
Melt 2 tablespoons butter with 1 tablespoon olive oil in a large skillet over medium-low heat. Add 3 large thinly sliced yellow onions and a pinch of salt, cook slowly 20 to 25 minutes until deeply golden and soft, stirring every few minutes so they don't burn. Add 2 minced garlic cloves in the last 1 to 2 minutes and stir.
In a bowl whisk together 1 (
5 oz) can condensed French onion soup, 1 cup sour cream, 1/2 cup milk, 1 teaspoon Worcestershire sauce if using, and 1 teaspoon fresh thyme leaves (or 1/2 teaspoon dried). Taste and season with salt and black pepper. Stir about half the caramelized onions into this mixture.
Arrange a single layer of potato slices in the prepared dish, overlap slightly. Season lightly with salt and pepper. Spoon about a third of the soup/onion sauce over the potatoes, then sprinkle about one third of the shredded Gruyere or Swiss cheese. Repeat to make another layer.
Finish with the remaining potato slices on top, pour the rest of the sauce evenly over everything so it seeps between layers. Press gently to compact a bit. Dot with the remaining 1 tablespoon butter if you like extra browning.
Cover the dish tightly with foil and bake 45 to 55 minutes, or until a knife or fork easily pierces the potatoes. If potatoes were sliced very thin you might need less time, check at 40 minutes.
Remove foil, sprinkle the remaining cheese over the top and spread 1 cup French fried onions evenly. Return to oven uncovered for 10 to 15 minutes until cheese is melted and edges are bubbly and onions are crisp and golden.
Let the casserole rest 10 minutes before serving so it sets up. Sprinkle extra French fried onions on top just before serving for extra crunch. Serve warm.

Notes

Below you’ll find my best estimate of this recipe’s nutrition facts. Treat the numbers as a guide rather than a rule—great food should nourish both body and spirit. Figures are approximate, and the website owner assumes no liability for any inaccuracies in this recipe.