French Onion Potatoes — Roasted Comfort Side Dish

The first bite is all savory-sweet: tender potatoes glazed with deeply caramelized onions and melted cheese that makes you sigh. French Onion Potatoes shows how humble spuds and onions turn into something indulgent and simple to make at home. I developed this version while cooking for busy weeknight service and refined it at home over eight tests to balance crisp edges, soft centers, and just the right onion-to-potato ratio. You’ll learn a few professional shortcuts here — from how to coax sweetness from onions without overcooking to the best roasting temperature for a crunchy top. Read on for the recipe, troubleshooting tips, and sensible make-ahead options so you can serve it any night of the week.

Why This Recipe Works

Slow caramelization concentrates onion flavor without burning, creating a rich glaze that clings to the potatoes.
A brief parboil softens potato centers so roasting produces crisp edges and a creamy interior.
High-heat finishing (220°C / 425°F) encourages browning and Maillard reactions for crunchy, savory bits.
A small amount of acid (sherry or white wine) lifts the deep onion flavor and prevents the dish from tasting flat.
Layering cheese near the end ensures melting without turning oily or separating.

Ingredients Breakdown

Potatoes: Use 900 g (2 lb) Yukon Gold or new potatoes for a waxy, creamy texture that holds shape. Russets will fall apart; use them only if you want a fluffier interior.
Onions: 450 g (3 large) yellow onions, thinly sliced. Yellow onions caramelize well; avoid sweet onions unless you like extra sweetness.
Butter + Oil: 30 g (2 tbsp) unsalted butter and 15 ml (1 tbsp) neutral oil for higher browning temperature. Butter gives flavor; oil prevents burning.
Sugar: 5 g (1 tsp) granulated sugar speeds and evens caramelization. Omit if you avoid added sugar.
Sherry or White Wine: 30 ml (2 tbsp) dry sherry or dry white wine to deglaze the pan and add brightness.
Beef or Vegetable Broth: 120 ml (1/2 cup) to loosen the onion fond and create a silky coating for the potatoes. Use low-sodium broth if watching salt.
Cheese: 100 g (1 cup) Gruyère or Swiss, grated. Cheddar is fine but will change the flavor and melt differently.
Fresh Thyme: 2 tsp fresh leaves or 1/2 tsp dried, for herbal lift.
Salt: 8 g (1 1/2 tsp) Diamond Crystal kosher salt; if using Morton’s, use 3/4 tsp (it’s denser).
Black Pepper: 1/2 tsp freshly ground.
Optional: 30 g (1/3 cup) breadcrumbs for a crisp top — add only if you enjoy a crunchy contrast.

Essential Equipment

Large heavy skillet (10–12-inch / 25–30 cm) for caramelizing onions; a wide pan increases evaporation and speeds browning. If you don’t have a heavy skillet, use a large sauté pan.
Roasting pan or rimmed baking sheet (large enough for a single layer) to encourage even browning. A cast-iron skillet works well in the oven.
Saucepot for parboiling potatoes.
Microplane or box grater for cheese.
Tongs and a sturdy spatula for stirring and tossing.
Instant-read thermometer (optional) to check doneness — potatoes should be tender when pierced with a fork.

Step-by-Step Instructions

Prep Time: 15 minutes; Cook Time: 45 minutes; Inactive Time: None; Total Time: 1 hour; Servings: 4

Step 1: Parboil the potatoes

Cut 900 g (2 lb) potatoes into 2–3 cm (1-inch) pieces so they roast evenly. Put them in cold salted water, bring to a simmer, and cook for 8–10 minutes until a knife slides in with slight resistance. Drain and let steam-dry for 2 minutes.

Step 2: Caramelize the onions

Heat 30 g (2 tbsp) butter and 15 ml (1 tbsp) oil in a 25–30 cm (10–12-inch) skillet over medium heat. Add 450 g (3 large) thinly sliced yellow onions and 5 g (1 tsp) sugar; cook, stirring every 2–3 minutes, until deep golden brown and very soft, about 25–30 minutes. Add 30 ml (2 tbsp) sherry or white wine, scrape the pan, and cook until liquid is mostly evaporated, about 1–2 minutes.

Step 3: Season and build flavor

Stir 120 ml (1/2 cup) broth, 2 tsp fresh thyme leaves, 8 g (1 1/2 tsp) Diamond Crystal kosher salt, and 1/2 tsp black pepper into the onions; simmer 2 minutes so the flavors marry. Taste and adjust salt; the onions should be richly savory with a glistening sheen.

Step 4: Toss potatoes with onion mix

Preheat oven to 220°C (425°F). In a large bowl, toss the drained potatoes with the onion mixture until every piece is coated, about 30 seconds. If using breadcrumbs, fold in 30 g (1/3 cup) now for exterior crunch. Transfer to a rimmed baking sheet in a single layer.

Step 5: Roast until crisp

Roast at 220°C (425°F) for 20–25 minutes, tossing halfway, until edges are golden and crisp and centers are tender when pierced, about 20–25 minutes. Remove, scatter 100 g (1 cup) grated Gruyère over the potatoes, and return to the oven for 3–5 minutes until the cheese melts and bubbles. Do not overbake — watch the cheese closely to prevent separation.

Expert Tips & Pro Techniques

Don’t rush the onions: low-and-slow develops deep flavor. If they brown too fast, reduce heat and add a splash of water.
Common mistake: crowding the sheet pan. Spread potatoes in a single layer for crisping; overcrowding causes steaming.
Parboil time matters: stop when a knife still meets slight resistance — overcooked pieces will crumble when tossed.
Make-ahead: Cook the onions and parboil the potatoes up to 24 hours ahead. Store separately in airtight containers; assemble and roast before serving.
Professional shortcut: Finish under the broiler for 1–2 minutes to caramelize cheese quickly — watch closely to avoid burning.
If you want an even browner crust, give the potatoes a quick shake in a colander after draining to roughen edges; texture helps browning.

Storage & Reheating

Refrigerator: Cool completely, then store in an airtight container for up to 3 days. Reheat only what you need.
Freezer: This dish is not ideal for long-term freezing; the texture suffers. If necessary, freeze in a shallow, airtight container for up to 1 month and expect softer potatoes after thawing.
Reheating: Reheat in a 175°C (350°F) oven for 10–12 minutes until warmed through and crisp at the edges. Avoid microwaving — it makes the potatoes mushy.

Variations & Substitutions

Gluten-Free: Omit breadcrumbs and use certified gluten-free broth. Everything else stays the same.
Vegetarian Swap: Use vegetable broth instead of beef or chicken broth; flavor stays rich thanks to long-cooked onions.
Cheesy Twice-Baked: Scoop roasted potatoes into a baking dish, mix with extra cheese and a splash of cream, then bake 10 minutes at 190°C (375°F) until bubbly.
Beefy Upgrade: Stir 150 g (5 oz) thinly sliced roast beef into the onions before tossing with potatoes for a main-course one-pan; increase broth by 30 ml (2 tbsp).
Lighter Version: Use 15 g (1 tbsp) olive oil instead of butter and omit cheese for a less rich side; roast times are unchanged.

Serving Suggestions & Pairings

Serve alongside roast chicken or pork and a green salad for a balanced meal. Pair with our chicken and orzo pairing for a complementary onion-forward dinner.
For a hearty plate, add sliced steak or sausages and a spoonful of Dijon mustard.
Garnish with chopped parsley and a sprinkle of flaky sea salt for brightness.
A dry white wine or malty brown ale pairs well with the sweet onion notes.

Nutrition Information
Serving size: about 1 cup (estimated); Recipe yields 4 servings.
Per serving (estimate):

Calories: 380 kcal
Total Fat: 16 g
Saturated Fat: 8 g
Cholesterol: 30 mg
Sodium: 620 mg
Total Carbohydrates: 46 g
Dietary Fiber: 4 g
Sugars: 6 g
Protein: 10 g

Nutrition values are estimates. Actual values may vary based on specific ingredients and preparation methods.

Frequently Asked Questions
Q: Why did my potatoes turn out dry?
A: Dry potatoes usually come from overbaking or starting with potatoes that cook too long during parboil. Parboil until just tender and watch oven time; remove when centers give with a fork.

Q: Can I make this without dairy?
A: Yes — omit the butter and cheese. Use 2 tbsp olive oil for sautéing and skip the cheese or finish with a dairy-free melt alternative. Texture and flavor will be slightly different.

Q: Can I double this recipe?
A: Yes, you can double it, but roast on two separate sheet pans so potatoes remain in a single layer. Roast both pans one at a time for best browning or rotate them in the oven halfway through.

Q: Can I prepare this the night before?
A: Absolutely. Caramelize the onions and parboil the potatoes up to 24 hours ahead. Store separately in the fridge and assemble just before roasting.

Q: How long does this keep in the fridge?
A: Stored in an airtight container, it keeps for up to 3 days. Reheat in a 175°C (350°F) oven to restore some crispness.

Q: What type of potato is best?
A: Yukon Gold or new potatoes are best for their waxy texture and creamy centers. Russets will get fluffier and may break down more during tossing.

Q: Can I use pre-made caramelized onions?
A: Yes, you can, but check for added sugars or preservatives. Adjust cooking liquids and seasoning because store-bought versions can be saltier or sweeter.

Conclusion

This French Onion Potatoes recipe is a simple way to add deep, cozy flavor to weeknight dinners or holiday spreads. For another take with similar flavors but different technique, read this French Onion Potatoes – South Your Mouth write-up that inspired some plating ideas. If you want a variation focused on roasted, cheesy bites, see this Roasted French Onion Potatoes Recipe | LaaLoosh for a complementary approach.