Mushroom & Leek Gratin

This comforting Mushroom & Leek Gratin layers tender sautéed leeks and earthy mushrooms in a creamy garlic sauce, topped with golden, bubbly cheese and crispy breadcrumbs. It’s a rich, satisfying side dish or vegetarian main that brings warmth and elegance to any table.

Why You’ll Love This recipe

You’ll love this Mushroom & Leek Gratin because it turns humble vegetables into a luxurious, crowd-pleasing dish with minimal fuss. The sweet, mild flavor of leeks pairs perfectly with savory mushrooms in a silky cream sauce, while the cheesy breadcrumb topping creates irresistible texture contrast.

It’s perfect for holidays, family dinners, or cozy weeknights, and it feels gourmet without being complicated. This recipe is naturally gluten-adaptable, make-ahead friendly, and delivers restaurant-quality comfort food that will have everyone asking for seconds.

Yield: 6 Serves

Mushroom & Leek Gratin

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Creamy Mushroom & Leek Gratin with golden cheesy crust — rich, comforting, and elegant!

Prep Time 20 minutes

Cook Time 35 minutes

Additional Time 10 minutes

Total Time 1 hour 5 minutes

Ingredients

• 1 lb (450g) mixed mushrooms, sliced
• 3 large leeks, white and light green parts only, thinly sliced
• 3 garlic cloves, minced
• 2 tablespoons butter
• 1 tablespoon olive oil
• 1 cup heavy cream
• 1 teaspoon fresh thyme leaves
• 1 cup Gruyère cheese, grated
• ½ cup Parmesan cheese, grated
• ½ cup panko breadcrumbs
• Salt and black pepper to taste
• Pinch of nutmeg (optional)

Instructions

1. Prep your vegetables – Preheat oven to 375°F (190°C). Clean and thinly slice the leeks and mushrooms. This ensures everything cooks evenly and beautifully.
2. Sauté the leeks – Heat butter and olive oil in a large skillet over medium heat. Add sliced leeks and cook gently for 8-10 minutes until soft and sweetly fragrant.
3. Add the mushrooms – Increase heat slightly and add mushrooms to the skillet. Cook for 6-8 minutes, stirring occasionally, until they release their moisture and turn golden brown.
4. Build the flavor base – Stir in minced garlic and fresh thyme. Cook for 1 minute until wonderfully aromatic. Season well with salt, pepper, and a pinch of nutmeg if using.
5. Create the creamy sauce – Pour in the heavy cream and bring to a gentle simmer. Let it cook for 3-4 minutes until slightly thickened and coats the vegetables nicely.
6. Transfer to baking dish – Pour the mushroom-leek mixture into a greased 8x10 or similar shallow baking dish, spreading it into an even layer.
7. Add the cheese layer – Sprinkle half the Gruyère and Parmesan cheeses evenly over the vegetables. This creates delicious melty pockets throughout.
8. Top with crunch – Mix remaining cheese with panko breadcrumbs and sprinkle generously over the top for that irresistible golden crust.
9. Bake to perfection – Place in the preheated oven and bake for 25-30 minutes until the sauce is bubbling and the topping is deep golden brown.
10. Rest and serve – Remove from oven and let rest for 10 minutes. This allows the gratin to set beautifully for clean, attractive slices. Serve warm as a stunning side or satisfying main.

Notes

This gratin pairs wonderfully with roasted chicken or steak. For extra richness, stir in a spoonful of crème fraîche before baking. Can be made in individual ramekins for elegant dinner parties.

Nutrition Information

Yield

6

Serving Size

1
Amount Per Serving Calories 591Total Fat 42gSaturated Fat 24gUnsaturated Fat 19gCholesterol 122mgSodium 880mgCarbohydrates 29gFiber 3gSugar 6gProtein 25g

The recipes and nutritional information on Yum Tonight are for informational purposes only. Always consult a healthcare provider for personalized dietary advice.

Recipe Tips and Tricks

• Slice leeks and mushrooms evenly for consistent cooking.
• Cook leeks slowly to bring out their natural sweetness.
• Thoroughly drain or cook off excess liquid from mushrooms to prevent a watery gratin.
• Use a shallow baking dish for the best crispy topping ratio.
• Let the gratin rest 5-10 minutes after baking for easier serving.
• Broil for the last 2 minutes for extra golden color on top.

Ingredients Notes

Fresh leeks provide a gentle onion-like sweetness and melt-in-your-mouth texture when cooked. A mix of mushrooms (cremini, button, and shiitake) adds deep umami and meaty bite.

Heavy cream and garlic create a rich, velvety sauce, while Gruyère and Parmesan cheeses deliver nutty depth and beautiful browning. Fresh thyme enhances the earthiness, and panko breadcrumbs give a light, crispy finish that contrasts the creamy filling.

Variations and Substitutions

Add spinach or kale for extra greens, or include crispy bacon or pancetta for a meaty version. Swap Gruyère with cheddar for a sharper taste or fontina for creaminess. For a lighter version, use half-and-half or milk instead of heavy cream.

Make it gluten-free with gluten-free breadcrumbs and a cornstarch slurry for thickening. Add a layer of thinly sliced potatoes for a heartier dish, or incorporate caramelized onions for deeper sweetness. Top with fried shallots for extra crunch.

Storage Options

Refrigerate leftovers in an airtight container for up to 4 days. Reheat in a 350°F oven until warmed through and topping is re-crisped.

This gratin can be assembled up to 24 hours ahead and baked just before serving. It also freezes well—bake fully, cool completely, then freeze up to 2 months. Thaw overnight in the fridge before reheating.

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