If you are a fan of comforting, creamy casseroles, then this Potato & Mushroom Gratin Recipe will quickly become one of your top favorites. It’s a luscious layering of thinly sliced russet potatoes, earthy portabello mushrooms, and a dreamy combination of Swiss, Gruyere, and Parmesan cheeses all bathed in a garlicky thyme-infused cream sauce. The result is a velvety, golden gratin with crisp browned edges and a tender, flavorful heart that makes every bite feel like a warm hug. This recipe is perfect for a cozy dinner or a special occasion side dish everyone will rave about.
Ingredients You’ll Need
Don’t be intimidated by the rich flavors here; the ingredients are simple, everyday staples that come together effortlessly to build depth and texture in this gratin. From the hearty russet potatoes to the fragrant thyme, each is essential for achieving the perfect balance of creaminess, earthiness, and melty cheesy goodness.
- 5 medium russet potatoes: Thinly sliced to create tender, melt-in-your-mouth layers that soak up all the flavors.
- 1 tablespoon olive oil: Used for sautéing mushrooms to bring out their rich umami.
- 8 ounces portabello mushrooms: Sliced and cooked to add a deep, meaty earthiness to the gratin.
- 1 ½ cups heavy cream: The luscious base that makes the gratin luxuriously creamy without being too heavy.
- 1 teaspoon thyme: Fresh and aromatic, it brightens the dish with subtle herbal notes.
- 1 teaspoon minced fresh garlic: Infuses the cream with a gentle savory kick.
- ½ cup shredded Swiss cheese: Adds a mild, nutty melty layer inside the gratin.
- 2 tablespoons grated Parmesan cheese: Sprinkled on top for flavorful golden crust and a touch of sharpness.
- Salt and pepper: To taste, enhancing and balancing all the ingredients.
- ½ cup shredded Gruyere cheese: The star cheese for a smooth, creamy texture and savoriness that melts beautifully.
How to Make Potato & Mushroom Gratin Recipe
Step 1: Prepare Your Oven and Dish
Start by preheating your oven to 400 degrees Fahrenheit. This high temperature helps develop a lovely browned top while cooking the potatoes perfectly through. Lightly spray a 2-quart oval baking dish with cooking spray to prevent sticking and set it aside for the layering process.
Step 2: Sauté the Mushrooms
In a small skillet, warm the olive oil over medium heat. Add the sliced portabello mushrooms and cook them for about 5 to 6 minutes. This step allows the mushrooms to release their moisture and concentrate their rich, savory flavor. Once softened, remove the skillet from heat and set the mushrooms aside. These juicy mushroom morsels will add body and earthiness to your gratin between the tender potato layers.
Step 3: Infuse the Cream Sauce
Next, gently heat the heavy cream in a small saucepan along with the minced garlic and thyme. Aim to warm the mixture thoroughly without reaching a boil — this helps infuse the cream with aromatic herbal and garlicky notes without curdling. Season the sauce with salt and pepper to create a perfectly seasoned base that will envelop each slice of potato and mushroom.
Step 4: Slice the Potatoes
Peel the russet potatoes carefully, then slice them thinly to about â…› inch thickness. Thin slices are key for tender layers that cook evenly and absorb that flavorful cream. Arrange the slices evenly in the prepared baking dish, creating a comforting base layer for your gratin masterpiece.
Step 5: Layer, Pour, and Sprinkle
Pour the warm cream sauce gently over the potato slices, letting it penetrate and coat every nook. Next, sprinkle the shredded Swiss and Gruyere cheeses over the cream-topped potatoes. Add the sautéed mushrooms evenly on top to distribute their earthy goodness throughout. Finally, dust the entire gratin generously with the grated Parmesan cheese — this will create a beautiful, golden crust as it bakes.
Step 6: Bake Until Golden and Bubbly
Place your gratin in the preheated oven and bake for about 45 minutes. You’ll know it’s ready when the top is golden brown, bubbly, and fragrant. Give it a rest of about 10 minutes out of the oven — this allows the cream to settle so your serving slices hold together beautifully and each bite is creamy and delicious.
How to Serve Potato & Mushroom Gratin Recipe
Garnishes
While the gratin is spectacular on its own, a sprinkle of fresh chopped parsley or a few sprigs of thyme on top adds a burst of color and freshness against the golden crust. For an extra touch, a light drizzle of truffle oil can elevate the earthy mushroom notes wonderfully.
Side Dishes
This Potato & Mushroom Gratin Recipe pairs beautifully with roasted or grilled meats like chicken, beef, or pork. It also complements crisp green salads and steamed green vegetables perfectly, balancing richness with freshness for a well-rounded meal.
Creative Ways to Present
For a fun twist, serve this gratin in individual small ramekins, making each portion feel special. Alternatively, layer the gratin with caramelized onions or add fresh herbs between layers for subtle variations. This recipe is versatile and adaptable without losing the comforting charm of the classic dish.
Make Ahead and Storage
Storing Leftovers
Once cooled, cover the gratin tightly with foil or plastic wrap and refrigerate for up to 3 days. The flavors deepen overnight, making leftovers even tastier. Just keep in mind that the top may lose some crispness, but the creamy layers inside remain luscious.
Freezing
This gratin freezes well if stored properly. Place it in an airtight container or wrap the dish securely with heavy-duty foil and plastic wrap to prevent freezer burn. Freeze for up to 2 months. When ready, thaw overnight in the refrigerator before reheating.
Reheating
Reheat leftovers in the oven at 350 degrees Fahrenheit until warmed through and bubbly, about 20 to 30 minutes. For a crispier top, uncover for the last 5 minutes. Avoid microwaving to maintain the gratin’s delicious texture and golden crust.
FAQs
Can I use other types of potatoes for this gratin?
While russet potatoes work best for their starchy texture and ability to hold cream, Yukon Golds can be used for a slightly creamier, buttery flavor. Avoid waxy potatoes as they may not cook to the creamy softness that makes this gratin so comforting.
Is it necessary to soak the potato slices before baking?
This recipe doesn’t require soaking. Since the potatoes cook slowly in the cream sauce, they soften beautifully without becoming mushy. Soaking is typically used to remove excess starch but isn’t needed here for best texture.
Can I make this Potato & Mushroom Gratin Recipe vegetarian?
Absolutely! This recipe is naturally vegetarian as it uses vegetable-based ingredients. Just be sure to use vegetarian-friendly cheese if that’s important to you.
What can I use if I don’t have Gruyere cheese?
Swiss cheese or even mozzarella can substitute in a pinch for Gruyere, but the flavor will be less complex. If possible, Gruyere adds a lovely nutty richness that complements the mushrooms and potatoes beautifully.
Can this gratin be made dairy-free?
You can try using a plant-based cream alternative and dairy-free cheeses, though the final texture and flavor will differ from the classic recipe. Sauté mushrooms with olive oil and use a rich non-dairy cream substitute to keep the dish creamy and satisfying.
Final Thoughts
This Potato & Mushroom Gratin Recipe is truly a heartwarming dish that brings comfort and elegance to any meal. Creamy, cheesy, and full of earthy flavors, it’s a wonderful way to showcase simple ingredients transformed into something special. I can’t wait for you to try it and make it a cherished classic at your table!
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Potato & Mushroom Gratin Recipe
- Prep Time: 15 minutes
- Cook Time: 45 minutes
- Total Time: 1 hour
- Yield: 6 to 6 servings
- Category: Side Dish
- Method: Baking
- Cuisine: French
- Diet: Vegetarian
Description
This Potato & Mushroom Gratin is a creamy, cheesy baked casserole featuring thinly sliced russet potatoes layered with sautéed portabello mushrooms and a rich herb-infused cream sauce. Topped with a blend of Swiss, Gruyere, and Parmesan cheeses, this gratin is golden and bubbly after baking, perfect as a comforting side dish or elegant vegetarian main course.
Ingredients
Vegetables
- 5 medium russet potatoes, sliced thinly (â…› inch thick)
- 8 ounces portabello mushrooms, sliced
Dairy & Cheese
- 1 ½ cups heavy cream
- ½ cup shredded Swiss cheese
- ½ cup shredded Gruyere cheese
- 2 tablespoons grated Parmesan cheese
Seasonings & Oils
- 1 tablespoon olive oil
- 1 teaspoon thyme
- 1 teaspoon minced fresh garlic
- Salt and pepper, to taste
Instructions
- Preheat the oven: Set your oven temperature to 400°F (204°C). Lightly spray a 2-quart oval baking dish with cooking spray to prevent sticking and set it aside to prepare for layering.
- Sauté the mushrooms: Heat the olive oil in a small skillet over medium heat. Add the sliced portabello mushrooms and cook for 5-6 minutes, allowing the mushrooms to release their moisture and soften. Once done, remove the skillet from heat and set mushrooms aside.
- Prepare the cream sauce: In a small saucepan, combine the heavy cream, minced fresh garlic, and thyme. Warm the mixture over medium heat until it is heated through but not boiling. Season the cream sauce with salt and pepper to your preference.
- Arrange the potatoes: Peel the potatoes and slice them into â…› inch thick slices if not already done. Place the sliced potatoes evenly in the prepared baking dish as the base layer.
- Assemble the gratin: Pour the warm cream sauce evenly over the potatoes in the baking dish. Sprinkle the shredded Swiss and Gruyere cheeses evenly on top, followed by the sautéed mushrooms. Finish by sprinkling the grated Parmesan cheese over the entire dish.
- Bake the gratin: Place the baking dish in the preheated oven and bake for 45 minutes or until the top is golden brown and bubbly. After baking, let the gratin rest for 10 minutes before serving to allow it to set.
Notes
- For best results, slice the potatoes as uniformly as possible to ensure even cooking.
- If preferred, substitute Gruyere with another melting cheese like mozzarella or fontina.
- You can prepare the gratin a few hours ahead; refrigerate uncovered before baking and increase baking time slightly.
- Allowing the gratin to sit after baking improves texture and makes serving easier.
- Use fresh thyme for optimal flavor, but dried thyme can be substituted at one-third the amount.
