Creamy Caramelized Onion & Parmesan Potato Gratin (Better, Richer, and Foolproof)
If you’re looking for a side dish that feels luxurious, comforting, and impressive without being overly complicated, this potato gratin is exactly what you need.
This version takes the classic French gratin and elevates it with deeply caramelized onions and nutty Parmesan cheese, creating a dish that’s rich, silky, and packed with flavor in every bite.
🥔 Why This Recipe Is Better
Richer Flavor
Caramelized onions add a deep, sweet-savory complexity you won’t get from a basic gratin.
Perfect Texture
Cream + potato starch creates a naturally thick, silky sauce—no flour needed.
Golden, Crispy Top
Parmesan melts and browns beautifully, giving you that irresistible crust.
Make-Ahead Friendly
Perfect for holidays, dinner parties, or meal prep.
🧾 Ingredients
3 lbs potatoes (Russet or Yukon Gold), thinly sliced
2 tbsp butter (for onions)
2 large onions, thinly sliced
2 cups heavy cream
1 cup finely grated Parmesan (+ extra for topping)
1½ tsp salt (divided)
1 tsp black pepper
2 tsp fresh thyme (or 1 tsp dried)
Butter or spray (for greasing dish)
👩🍳 Step-by-Step Instructions
1. Preheat Oven
Set oven to 375°F (190°C) and grease a 9×13-inch baking dish.
2. Caramelize the Onions
Cook onions in butter over medium heat for 20–25 minutes, stirring occasionally until soft, golden, and sweet.
This step is key—don’t rush it.
3. Make the Cream Mixture
Mix cream, Parmesan, salt, pepper, thyme, and caramelized onions.
4. Slice the Potatoes
Cut into thin (⅛-inch) slices for even cooking.
5. Assemble
Layer potatoes in the dish, then pour cream mixture evenly over them.
6. Bake Covered
Cover with foil and bake 45–55 minutes until potatoes are tender.
7. Bake Uncovered
Remove foil and bake another 15–20 minutes until golden and bubbling.
8. Rest Before Serving
Let sit for 10–15 minutes so the sauce thickens properly.
🔥 Pro Tips for Perfect Gratin
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