French Onion Potatoes Au Gratin Recipe: Cheesy Comfort Classic

Caramelized layers and gooey cheese combine for an indulgence that delights every palate.

By Medha deb

Created on Sep 17, 2025

Caramelized layers and gooey cheese combine for an indulgence that delights every palate.

French Onion Potatoes Au Gratin: A Cozy, Crowd-Pleasing Classic

French Onion Potatoes Au Gratin is a decadent twist on a beloved comfort food staple, combining the soulful warmth of caramelized onions with the hearty, cheesy goodness of classic au gratin potatoes. Inspired by The Pioneer Woman, this recipe layers tender, thinly sliced russet potatoes, a luscious sauce, and two layers of melty cheeses, then accents the dish with the rich, deep flavor of French onion soup. The result is a side dish that’s rich, creamy, and impossible to resist—perfect for holidays, family gatherings, or anytime you want to treat yourself to something truly special.

Why This Recipe Stands Out

Traditional au gratin potatoes are already a favorite for their creamy texture and golden, cheesy top. But this version elevates the dish by incorporating the deep, sweet, and savory taste of caramelized onions, reminiscent of classic French onion soup. The blend of Gruyère, Swiss, and Parmesan cheeses creates a harmonious melt, while heavy cream and whole milk ensure a velvety, lush interior. Fresh thyme and a splash of sherry add sophisticated notes, making this dish as elegant as it is comforting.

Ingredients You’ll Need

Ingredient	Amount
Salted butter	4 Tbsp (plus extra for dish)
Olive oil	2 Tbsp
Onions	5, thinly sliced
Kosher salt	1 1/2 tsp
Black pepper	To taste
Sugar	1 tsp
Fresh thyme	1 Tbsp, chopped
Dry sherry	1/4 cup
Low-sodium beef broth	1/2 cup
All-purpose flour	2 Tbsp
Heavy cream	1 1/2 cups
Whole milk	1 1/2 cups
Freshly grated nutmeg	1/4 tsp
Gruyère cheese	6 oz, shredded
Swiss cheese	6 oz, shredded
Russet potatoes	5 large, peeled, halved, sliced 1/4 inch thick
Parmesan cheese	1/4 cup, grated
Fresh chives	For topping

Step-by-Step Recipe Instructions

1. Prepare the Baking Dish and Preheat Oven

Preheat your oven to 375°F.
Butter a 9-by-13-inch baking dish.

2. Caramelize the Onions

Heat olive oil and 2 Tbsp butter in a large skillet over medium-low heat.
Add the sliced onions, 1 tsp salt, black pepper to taste, and sugar. Stir to combine.
Cover and cook for 10 minutes, stirring once.
Uncover, increase heat to medium, and cook, stirring, for another 10 minutes.
Add fresh thyme, sherry, and beef broth. Cook, stirring, until liquid evaporates and onions are deeply caramelized—about 15 minutes. Set aside.

3. Make the Cream Sauce

In a Dutch oven, melt remaining 2 Tbsp butter over medium heat.
Add flour and cook, stirring, for 1 minute.
Whisk in heavy cream and whole milk, remaining salt, and nutmeg. Bring to a simmer, whisking until smooth and thickened—about 2–3 minutes.
Remove from heat and stir in all but 1/2 cup each of the Gruyère and Swiss cheeses until melted.
Stir in the sliced potatoes, coating them well with the sauce.

4. Layer and Bake

Layer half the potatoes in the buttered baking dish.
Top with half the caramelized onions.
Repeat with remaining potatoes and onions.
Sprinkle reserved cheeses and Parmesan on top.
Cover with foil (tented so it doesn’t touch the cheese) and bake for 45–55 minutes, until potatoes are tender.
Uncover and bake until golden brown, about 20–25 minutes.
Let rest for 20 minutes, then top with fresh chives.

Tips for the Best French Onion Potatoes Au Gratin

Onion Caramelization: Be patient with caramelizing the onions—low and slow is key for maximum depth of flavor. Don’t rush this step; darker onions mean more flavor.
Cheese Selection: Use high-quality, freshly grated cheeses for optimum meltiness and taste. Pre-shredded cheeses often contain anti-caking agents that can make the texture less creamy.
Potatoes: Russet potatoes are traditional for au gratin due to their starchiness, but Yukon Golds can also be used for a slightly creamier result.
Make-Ahead: Assemble the dish a day ahead (up to adding the reserved cheese topping) and refrigerate. Bring to room temperature before baking as directed.
Serving: Always let the dish rest after baking—this helps the sauce set and makes slicing easier.

Recipe Variations and Substitutions

This versatile recipe can be tailored to your tastes or dietary needs:

Vegetarian Option: Substitute vegetable broth for beef broth.
Lower Fat: Use half-and-half or evaporated milk instead of heavy cream and whole milk.
Cheese Variations: Experiment with different melting cheeses like fontina, cheddar, or smoked Gouda for new flavors.
Add-Ins: Consider adding a layer of sautéed mushrooms, crispy bacon bits, or a handful of fresh spinach for extra layers of flavor.

Serving Suggestions and Pairings

Pairings

French Onion Potatoes Au Gratin makes a stunning side dish for holiday feasts, family dinners, or special occasions. Try pairing it with:

Roasted beef, turkey, or pork
Seared steak
Herb-roasted chicken
A simple green salad with vinaigrette to balance the richness

Presentation

Sprinkle with chopped fresh chives for a pop of color and fresh flavor. Serve hot from the oven for the best texture and aroma.

Making Ahead and Storage

Make Ahead: Assemble the dish up to a day in advance; bake just before serving.
Storage: Leftovers can be refrigerated for up to 3 days. Reheat in the oven or microwave until warmed through.
Freezing: This dish does not freeze well due to the creamy sauce.

Frequently Asked Questions (FAQs)

Can I Use a Different Type of Potato?

Russet potatoes are ideal for their starch content, which helps thicken the sauce and creates a fluffy texture. Yukon Gold potatoes can also be used for a creamier texture, but they may absorb less liquid and be less fluffy.

Can I Use Pre-Shredded Cheese?

Pre-shredded cheese often contains anti-caking agents that can affect melting and texture. For the creamiest, smoothest result, always grate your own cheese from a block.

How Do I Keep the Potatoes from Browning Before Baking?

The cream sauce helps prevent browning, but if you’re slicing potatoes ahead of time, place them in a bowl of cold water to prevent oxidation. Drain and pat dry before using.

Can I Make This Dish Dairy-Free?

You can substitute dairy-free milk and cheese alternatives, but the flavor and texture will be different from the original recipe. For best results, look for plant-based cheese that melts well and use a rich, unsweetened non-dairy cream.

How Do I Know When the Potatoes Are Done?

The potatoes are ready when a paring knife inserted into the center goes in easily, with no resistance, and the top is golden-brown and bubbly.

The Story Behind the Recipe

Potatoes au gratin traces its roots to French cuisine, where “gratin” refers to a browned, often cheesy, crust. The addition of caramelized onions in this version takes inspiration from French onion soup, melding two classic French dishes into one comforting bake. The Pioneer Woman’s recipe embraces both tradition and innovation, offering a luscious, crowd-pleasing side that’s perfect for everything from Sunday suppers to holiday tables.

Conclusion

French Onion Potatoes Au Gratin is more than just a side dish—it’s a celebration of comfort, flavor, and texture. The layers of creamy, cheesy potatoes and savory caramelized onions are sure to become a favorite in your recipe collection. With tips for making ahead, easy variations, and serving suggestions, this recipe is a keeper for both everyday dinners and special occasions. Enjoy the cozy, indulgent flavors and share the warmth with your loved ones.

References

Author

medha deb

Medha Deb is an editor with a master's degree in Applied Linguistics from the University of Hyderabad. She believes that her qualification has helped her develop a deep understanding of language and its application in various contexts.

Read full bio of medha deb