Step 1: Preheat and Prepare
- Preheat your oven to 375°F (190°C). Grease a large baking dish with butter.
Step 2: Layer the Vegetables
- Layer the root vegetables and onion in the prepared baking dish, alternating them and seasoning each layer with salt, pepper, and minced garlic. Sprinkle thyme and nutmeg (if using) throughout the layers.
Step 3: Prepare the Cream Sauce
- In a saucepan, combine the heavy cream and milk. Bring to a simmer over medium heat. Season with a little salt and pepper. Pour this
mixture evenly over the layered root vegetables in the baking dish, ensuring it seeps into the layers.
Step 4: Add Cheese
- Sprinkle the grated Gruyère cheese evenly over the top of the vegetables. Then, add a layer of grated Parmesan cheese on top of the Gruyère. The cheeses will melt and brown in the oven, creating a deliciously golden crust.
Step 5: Bake the Gratin
- Cover the baking dish with aluminum foil and bake in the preheated oven for about 40 minutes. After 40 minutes, remove the foil and continue to bake for another 20-30 minutes, or until the vegetables are tender when pierced with a knife and the top is golden and bubbly.
Step 6: Rest and Serve
- Let the gratin rest for about 10 minutes after removing it from the oven. This allows the sauce to thicken slightly and makes it easier to serve.
- Serve warm as a side dish to your favorite protein, such as roasted chicken, beef, or fish. This gratin also pairs beautifully with a simple green salad for a lighter contrast.
Tips:
- Slicing the Vegetables: Use a mandoline slicer for consistent, thin slices of the root vegetables. This ensures even cooking and a better texture in the gratin.
- Cheese Variations: Feel free to experiment with different types of cheese based on your preference. A combination of cheeses can add depth and complexity to the flavor.
- Making Ahead: You can assemble the gratin a day ahead and refrigerate it covered. Remove it from the refrigerator about 30 minutes before baking to bring it closer to room temperature, which helps it cook more evenly.
- Broiling for a Crust: If the top of the gratin isn’t as golden as you’d like by the end of baking, you can broil it for a few minutes. Keep an eye on it to prevent burning.
Enjoy your Cheesy Root Vegetable Gratin, a celebration of root vegetables in a rich, creamy, and cheesy sauce that’s sure to comfort and satisfy.