Name: Cheesy French Onion Gratin
Prep time: 30 min
Cook time: 5 min
Total time: 35 min
Yield: 4 servings
Cuisine: French
Ingredients: 600 g yellow onions; 30 g unsalted butter; 15 ml olive oil; 2 garlic; 2 g fresh thyme; 150 ml heavy cream; 40 g vegetarian parmesan cheese; 60 g gruyere cheese; 3 g kosher salt; 1 g black pepper

Equipment

Large oven-safe skillet

or Standard skillet for stovetop, transferring to a baking dish for the oven

Chef's knife

Cutting board

Cheese grater

Ingredients

4 servings

Base

600 g yellow onions, peeled and sliced into thin half-moons
30 g unsalted butter, room temperature
15 ml olive oil
2 garlic, minced
2 g fresh thyme, leaves stripped and finely chopped

Sauce and Topping

150 ml heavy cream
40 g vegetarian parmesan cheese, freshly grated
60 g gruyere cheese, freshly grated
3 g kosher salt
1 g black pepper, freshly cracked

Nutrition (per serving)

380

Calories

11g

Protein

17g

Carbs

31g

Fat

Fiber

Sugar

534mg

Sodium

Method

Prepare your ingredients by slicing the onions into even half-moons, mincing the garlic, and freshly grating both cheeses.

Preheat your broiler to high, approximately 260°C or 500°F.

Heat the butter and olive oil in a large oven-safe skillet over medium heat. Add the sliced onions, season with the kosher salt and black pepper, and saute until they are very tender and deeply translucent. This should take about 15 minutes.

15mLook for: translucent, reduced in volume, and slightly goldenFeel: very soft and yielding to the spoon

Stir in the minced garlic and fresh thyme, cooking for 1 minute until fragrant. Pour in the heavy cream and simmer gently until the liquid reduces and coats the onions thickly, roughly 4 minutes.

5mLook for: cream is bubbling evenly and visibly thickened, clinging perfectly to the onions

Remove the skillet from the stovetop heat. Evenly sprinkle the grated gruyere and vegetarian parmesan over the entire surface of the creamy onions.

Transfer the skillet to the oven and broil for 4 to 5 minutes. Watch closely until the cheese is bubbling, thoroughly melted, and forms a rich golden-brown crust.

5mLook for: deep golden brown patches across the top with vigorous bubbling around the edges

Carefully remove the bubbling skillet from the oven. Let the gratin rest at room temperature for 5 minutes before serving to allow the molten cream and cheese to set slightly.

5mFeel: skillet is still hot but bubbling has subsided

Chef's Notes

Using a mix of butter and olive oil elevates the flavor while preventing the milk solids in the butter from burning during the extended cooking time.
Always grate your own cheese for a gratin. Pre-shredded cheeses are coated in starches like cellulose that inhibit smooth melting and can impart a gritty texture to the final dish.
Traditional Parmigiano-Reggiano contains animal rennet. To keep this recipe strictly vegetarian, you must specifically source a certified vegetarian hard cheese.
An oven-safe cast iron or heavy stainless steel skillet is essential here to transition seamlessly from stovetop to high-heat broiler without warping or cracking.