Caramelized Onion and White Cheddar Gratin

Name: Caramelized Onion and White Cheddar Gratin
Prep time: 15 min
Cook time: 40 min
Total time: 55 min
Yield: 6 servings
Ingredients: 4 large onions, thinly sliced; 2 tablespoons butter; 1 teaspoon salt; 1/2 teaspoon black pepper; 1 cup heavy cream; 2 cups white cheddar cheese, grated; 1/2 cup breadcrumbs; 2 tablespoons fresh thyme, chopped

Highlighted under: Comfort Food

I absolutely love this Caramelized Onion and White Cheddar Gratin. The creamy blend of flavors combined with the rich sweetness of caramelized onions creates an unforgettable dish that warms the soul. I often make this gratin as a side for family gatherings and special occasions. The gooey cheese paired with the perfectly browned onions is simply irresistible, and it’s a comforting dish that everyone can enjoy. Plus, it’s surprisingly easy to prepare, making it a go-to recipe in my kitchen.

Created by

Emily

Last updated on 2026-01-08T12:02:36.432Z

As I was experimenting with different gratin recipes, I discovered that caramelizing onions brings out their natural sweetness, enhancing any dish. After trying several cheese combinations, I found that white cheddar provided a perfect balance, melting beautifully to form a rich, creamy texture. I was amazed at how much depth this simple adjustment added to the classic gratin recipe.

Another exciting tip I learned was to finish the dish under the broiler for a few minutes. This technique gives the top a golden, crispy crust that contrasts wonderfully with the creamy filling below. It’s a method I now swear by, ensuring that every bite has that perfect combination of textures.

        Why You'll Love This Recipe
        Rich, sweet flavor from perfectly caramelized onions
Creamy, melty white cheddar cheese that elevates the dish
A delightful crispy top that adds wonderful texture

      

The Art of Caramelizing Onions

Caramelizing onions is an essential step that truly shapes the flavor profile of this gratin. Begin by slicing your onions thinly to ensure they cook evenly. A large skillet with a wide base works best, as it allows the onions to spread out and caramelize instead of steaming. Aim for medium heat; if it’s too high, you risk burning the onions before they're fully sweetened. Stir them occasionally to promote even browning and allow those natural sugars to develop—a process that usually takes about 25 minutes.

Keep a close eye on the onions as they caramelize. They should turn a deep golden brown with a rich, sweet aroma filling your kitchen. If you find that they’re browning too quickly, lower the heat as needed. Accomplished properly, the sweetness of the caramelized onions will heighten the overall flavor of the dish and provide a delicious contrast to the creamy cheddar.

Choosing the Right Cheese

For this gratin, using a good quality white cheddar is crucial for achieving that signature creamy texture and robust flavor. White cheddar tends to melt beautifully, while imparting a slightly sharp taste that complements the sweetness of the onions. If you're looking for a different flavor profile, feel free to mix in a bit of Gruyère or Fontina cheese for added complexity. Just ensure whatever cheese you choose melts well, as a gritty or clumpy melted cheese can detract from the gratin’s creaminess.

When preparing your cheese mixture, make sure the heavy cream is room temperature for a smoother blend. Mixing in fresh thyme not only adds an earthy note but also balances the rich flavors of the cheese and onions. This can also be a great opportunity to experiment with other herbs like rosemary or chives—just keep the quantities in mind for nuanced flavor without overwhelming the dish.

Ingredients

Gather the following ingredients to create this delicious gratin:

Ingredients

4 large onions, thinly sliced
2 tablespoons butter
1 teaspoon salt
1/2 teaspoon black pepper
1 cup heavy cream
2 cups white cheddar cheese, grated
1/2 cup breadcrumbs
2 tablespoons fresh thyme, chopped

Make sure to have all your ingredients prepped before you start cooking to streamline the process.

Instructions

Follow these steps to make your Caramelized Onion and White Cheddar Gratin:

Caramelize the Onions

In a large skillet, melt the butter over medium heat. Add the sliced onions and sauté for about 25 minutes, stirring occasionally, until the onions are golden and caramelized. Season with salt and pepper.

Prepare the Cheese Mixture

In a bowl, mix the heavy cream with half of the grated white cheddar and fresh thyme. Stir until well combined.

Assemble the Gratin

In a greased baking dish, layer the caramelized onions, then pour the cheese mixture over them. Top with the remaining cheddar and breadcrumbs.

Bake the Gratin

Preheat your oven to 350°F (175°C) and bake the gratin for about 30 minutes, or until the cheese is bubbly and golden.

Broil for Extra Crisp

For a crispy top, switch the oven to broil and cook for an additional 5 minutes, watching closely to prevent burning.

Serve

Let the gratin cool slightly before serving. Enjoy this rich and creamy dish with your favorite main course!

Enjoy your Caramelized Onion and White Cheddar Gratin as a side dish or as a delicious snack!

Pro Tips

For added depth, try incorporating a splash of balsamic vinegar when caramelizing the onions to enhance their sweetness further.

Make-Ahead Tips

This gratin can be prepared in advance, making it ideal for busy gatherings. After assembling the layers in the baking dish, cover it tightly with plastic wrap and store it in the refrigerator for up to 24 hours. When you're ready to bake, simply remove the wrap and let it sit at room temperature for about 15 minutes before placing it in the oven. This helps the gratin bake evenly without the edges burning while the center remains cool.

Leftovers can be stored in an airtight container for up to three days. To reheat, place the gratin in a preheated oven at 350°F (175°C) for about 20 minutes. If you prefer, you can microwave individual portions, although oven reheating generally retains the dish's original texture better.

Serving Suggestions

This Caramelized Onion and White Cheddar Gratin pairs wonderfully with a variety of main dishes. Consider serving it alongside a roasted chicken, grilled steak, or a succulent pork chop to bring out the gratin's rich flavors. For a vegetarian option, it makes a delightful accompaniment to a salad of mixed greens topped with roasted vegetables.

To enhance the overall experience, consider adding a fresh side salad with a light vinaigrette to balance the richness of the gratin. The acidity from the dressing helps to cut through the creaminess and provides a refreshing contrast that elevates the entire meal.

Questions About Recipes

→ Can I use other types of cheese?

Absolutely! Gruyère or Fontina also work well if you're looking for different flavors.

→ Can I make this dish ahead of time?

Yes, you can prepare it and keep it covered in the fridge for up to two days. Just reheat before serving.

→ How do I store leftovers?

Store leftovers in an airtight container in the fridge for up to 3 days. Reheat in the oven for the best results.

→ Can I add vegetables to the gratin?

You can definitely add vegetables like spinach or mushrooms for an extra twist and added nutrition!