How to Make French Mushroom and Onion Gratin

French Mushroom and Onion Gratin is a delightful dish that perfectly combines the rich flavors of sautéed mushrooms and onions, enveloped in a creamy, cheesy sauce. This rustic French classic is ideal for a cozy dinner or as a side dish to impress your guests. Follow this detailed recipe to create your own mouthwatering gratin.

Ingredients

2 cups of fresh mushrooms (your choice: cremini, button, or shiitake)
2 large onions, thinly sliced
2 tablespoons of olive oil
3 cloves of garlic, minced
1 cup of heavy cream
1 cup of grated Gruyère cheese
1 cup of grated Parmesan cheese
1 teaspoon of fresh thyme or ½ teaspoon of dried thyme
Salt and pepper to taste
1 cup of breadcrumbs (optional, for a crunchy topping)

Instructions

Step 1: Prepare the Vegetables

Start by cleaning the mushrooms. Use a damp cloth to wipe off any dirt. Slice the mushrooms and set them aside. Next, peel and thinly slice the onions.

Step 2: Sauté the Onions

In a large skillet, heat the olive oil over medium heat. Add the sliced onions and a pinch of salt. Sauté for about 10-15 minutes until the onions are caramelized and golden brown. Stir occasionally to prevent sticking.

Step 3: Add the Mushrooms

Once the onions are nicely caramelized, add the minced garlic and sauté for an additional minute. Then, incorporate the sliced mushrooms into the skillet. Cook for another 5-7 minutes until the mushrooms are tender and have released their moisture.

Step 4: Make the Creamy Sauce

Reduce the heat to low and pour in the heavy cream. Add the fresh or dried thyme, salt, and pepper to taste. Stir well, allowing the mixture to simmer gently for about 5 minutes. Remove the skillet from the heat.

Step 5: Assemble the Gratin

Preheat your oven to 375°F (190°C). In a baking dish, combine the mushroom and onion mixture with half of the grated Gruyère cheese. Mix well to ensure the cheese is evenly distributed. Layer the remaining Gruyère cheese and the grated Parmesan cheese on top. If you prefer a crispy topping, sprinkle breadcrumbs evenly over the cheese layer.

Step 6: Bake the Gratin

Place the baking dish in the preheated oven and bake for about 25-30 minutes or until the top is golden brown and bubbling. If you notice that the top is browning too quickly, you can cover the dish with aluminum foil for the last 10 minutes of baking.

Step 7: Serve and Enjoy

Once baked, remove the gratin from the oven and let it sit for a few minutes before serving. This dish can be enjoyed hot or warm, and it pairs perfectly with a fresh salad or crusty bread. Enjoy the delightful flavors of your homemade French Mushroom and Onion Gratin!

Tips for the Perfect Gratin

Feel free to experiment with different mushroom varieties for unique flavors.
For extra richness, you can add a splash of white wine to the onions while they sauté.
To enhance the taste, consider adding a pinch of nutmeg to the cream mixture.

Making French Mushroom and Onion Gratin at home is not only easy but allows you to customize it according to your taste preferences. Give this comforting dish a try and savor the delicious results!