Creamed Onion Gratin

Perfectly tender onions baked in a creamy bechamel sauce with white wine, fresh thyme and, grated parmesan cheese. Bubbling, golden brown, creamed onion gratin is a perfect side dish for weeknight dinners or holiday meals!

an oval copper baking dish filled with creamed onion gratin with a gold spoon and beige tea towel

This crazy delicious creamed onion gratin is so easy to make! I serve it for Thanksgiving and Christmas dinner and it’s always a hit at both! As an added bonus the leftovers are just as yummy the next day.

Creamed onion gratin combines the best elements of two of my favorite side dishes; creamed pearl onions and potato gratin. The result is super soft onions smothered in a creamy, cheesy bechamel sauce with a crispy, golden brown bubbling crust. You must make this recipe it is seriously heaven!

Ingredients You’ll Need:

Here’s everything you’ll need to make creamed onion gratin: medium-sized yellow onions, cream, butter, olive oil, flour, parmesan cheese, fresh thyme, garlic, white wine, and a pinch of nutmeg.

recipe ingredients on a blue bakground, a cup of cream, a small plate with flour, onions in a baking dish, white wine, fresh thyme etc.

Recipe Steps

Step 1. Bake the Onions

Toss the onions with the olive oil and a pinch of salt. Place in a medium-sized casserole dish. Pour the white wine over the onions. Bake for 1 hour or until the onions are completely tender, stirring halfway through.

a small sauce pot filled with bechamel sauce and an oval copper baking dish filled with quartered onions

Step 2. Make the Bechamel

In a small sauce pot melt the butter over medium heat; add the flour, and cook, stirring, until smooth and a pale golden color, about 1 minute. Next, whisk in the cream, half the parmesan cheese, thyme leaves, nutmeg and, grated garlic. Cook, whisking, until thickened, about 5 minutes. Turn off the heat, taste and season with salt and pepper.

a pot of bechamel sauce being poured into a copper baking dish filled with baked onions

Step 3. Broil

Turn on your oven’s broiler. Pour the sauce evenly over onions. Sprinkle with the rest of the grated parmesan cheese. Broil until the cheese is melted and golden brown on top, about 2 minutes. Pro Tip: Place the baking dish on top of a sheet tray to make it easier to take the baking dish in and out of the oven, and to catch any spilled cream that may bubble over the side.

FAQs

Can this recipe be prepped in advance?

Yes, you can make this recipe up to two days ahead of time. To prep creamed onion gratin follow the first two steps and pour the sauce over the onions. Wrap the entire baking dish in foil then refrigerate. To reheat and finish, preheat the oven to 350, remove the foil and bake for 10 minutes, then broil 1 to 2 minutes until golden brown and bubbling. 

What should you serve with Creamed Onion Gratin?

This onion gratin pairs well with roasted, chicken, beef, or fish as well as side dishes like; a simple side salad, roasted vegetables, or French green beans.

Can I use other cheeses besides parmesan for this recipe?

Yes, you can substitute gruyere cheese, manchego, asiago, or gouda.

an oval baking dish filled with creamed onion gratin and a gold spoon, grey tea towel, cranberry sauce and green beans in the background.

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Creamed Onion Gratin

Perfectly tender onions baked in a creamy bechamel sauce with white wine, fresh thyme and, grated parmesan cheese. Bubbling, golden brown, creamed onion gratin is a perfect side dish for weeknight dinners or holiday meals!
5 from 2 votes
Print Pin Rate
Prep Time: 15 minutes
Cook Time: 1 hour
Servings: 4
Calories: 489kcal

Ingredients

  • 3 medium yellow onions peeled and, cut into 8 pieces
  • 1/4 c dry white wine
  • 2 tbsp olive oil
  • 2 tbsp butter
  • 2 tbsp flour
  • 1 c heavy cream
  • 1 c grated parmesan cheese divided
  • 1 clove garlic grated
  • 1 tbsp thyme leaves
  • 1 pinch nutmeg
  • salt and pepper

Instructions

  • Heat oven to 350°. Toss the onions with the olive oil and a pinch of salt. Place in a medium-sized casserole dish, with a baking tray underneath to catch any drips or spills. Pour the white wine over the onions. Bake for 1 hour or until the onions are completely tender, stirring halfway through.
  • In a small sauce pot melt the butter over medium heat; add the flour, and cook, stirring, until smooth and a pale golden color, about 1 minute. Next, whisk in the cream, half the parmesan cheese, thyme leaves, nutmeg and, grated garlic. Cook, whisking, until thickened, about 5 minutes. Turn off the heat, taste, and season with salt and pepper.
  • Turn on your oven's broiler. Pour the sauce evenly over onions. Sprinkle with the rest of the grated parmesan cheese. Broil until the cheese is melted and golden brown on top, about 2 minutes.

Notes

Make-Ahead Instructions:
  • Yes, you can make this recipe up to two days ahead of time. To prep creamed onion gratin follow the first two steps and pour the sauce over the onions. Wrap the entire baking dish in foil then refrigerate. To reheat and finish, preheat the oven to 350, remove the foil and bake for 10 minutes, then broil 1 to 2 minutes until golden brown and bubbling.
Ingredient Substitutions:
  • White Wine: If you prefer to not cook with alcohol you can substitute water with a tsp of champagne vinegar. 
  • Parmesan Cheese: Asiago, Manchego, Gouda or Gruyere 
  • Flour: To make this recipe gluten-free use a gluten-free flour like Cup4Cup.
Equipment:
Copper Gratin Pan | Baking Trays  

Nutrition

Calories: 489kcal | Carbohydrates: 14g | Protein: 12g | Fat: 42g | Saturated Fat: 23g | Cholesterol: 119mg | Sodium: 460mg | Potassium: 218mg | Fiber: 2g | Sugar: 4g | Vitamin A: 1351IU | Vitamin C: 10mg | Calcium: 342mg | Iron: 1mg
Did you make this recipe?Share a picture on Instagram and tag me: @Craving_California and use the hashtag: #CravingCalifornia!

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