Creamy Potato, Mushroom, and Leek Gratin layers thin coins of potato with golden mushrooms and melting leeks, all under cream and Parmesan. It bakes into one bubbling, golden-edged dish. This is the side that quietly becomes the reason people came.
Craving the ultimate comfort food? Look no further! This Creamy Potato, Mushroom, and Leek Gratin is a hug in a dish. We’re talking tenderly layered potatoes, earthy mushrooms, and sweet, delicate leeks, all bathed in a luscious, rosemary-infused cream sauce and baked to golden, bubbly perfection with a generous blanket of Parmesan cheese. It’s elegant enough for a special dinner but simple enough for a cozy weeknight meal. Get ready to fall in love with your new favorite casserole!
Recipe at a Glance
• Prep Time: 35 minutes
• Cook Time: 40 minutes
• Stand Time: 10 minutes
• Servings: 4
Ingredients
• 1 pound / 450g (15.9 oz) potatoes, about 3 medium, sliced 1/4-inch / 6mm thick
• 2 tablespoons (30 ml / 1 fl oz) olive oil or vegetable oil, divided
• 8 ounces / 225g (7.9 oz) fresh mushrooms, sliced
• 2/3 cup (720 ml) thinly sliced leeks, from about 2 medium leeks
• 2 cloves garlic, minced
• 1/2 teaspoon (10 ml / 0.3 fl oz) dried rosemary, crushed
• 1/4 teaspoon salt
• 1/2 cup / 120ml heavy whipping cream
• 3/4 cup / 3 ounces / 85g (3 oz) shredded Parmesan cheese, divided
• Sour cream, for serving, optional
Instructions
1. Preheat your oven to 400°F / 200°C. Lightly grease a 1.5-quart soufflé dish or casserole. In a medium saucepan, par-boil the potato slices in lightly salted water for 3 minutes. They will not be fully tender. Drain well and set aside.
2. While the potatoes cook, heat 1 tablespoon (15 ml / 0.5 fl oz) of oil in a large skillet over medium heat. Add the mushrooms, leeks, garlic, rosemary, and salt. Sauté, stirring occasionally, until the leeks are tender.
3. Stir the heavy cream into the skillet. Bring the mixture to a boil, then immediately reduce the heat and simmer gently for about 30 seconds, or until the sauce has slightly thickened.
4. To assemble, arrange a third of the potato slices in the bottom of your prepared dish, overlapping them as needed. Spoon one-third of the leek mixture over the potatoes and sprinkle with 1/4 cup (960 ml) of the Parmesan cheese. Repeat the layers once more. Top with the remaining potatoes and the final third of the leek mixture. Drizzle with the remaining 1 tablespoon (15 ml / 0.5 fl oz) of oil.
5. Bake, uncovered, for 30 minutes. Carefully remove from the oven and sprinkle the remaining 1/4 cup (960 ml) of Parmesan cheese over the top. Return to the oven and bake for an additional 5 to 10 minutes, until the potatoes are fork-tender and the top is golden and bubbly.
6. Let the gratin stand for 10 minutes before serving to allow it to set. Serve warm, with a dollop of sour cream if you like.
Nutritional Information
• PER SERVING: 345 calories, 24 g (0.85 oz) total fat (11 g / 0.39 oz saturated fat), 54 mg cholesterol, 398 mg sodium, 26 g (0.92 oz) carbohydrates, 3 g (0.11 oz) fiber, 11 g (0.39 oz) protein.
Pro Tips
• for the Perfect Gratin
• Use a waxy potato variety like Yukon Gold or red potatoes. They hold their shape better during baking and result in a creamier texture.
• Leeks can be gritty. To clean them properly, slice them first, then place them in a bowl of cold water. Swish them around to release any dirt, then lift them out with a slotted spoon.
• Feel free to swap the Parmesan for other flavorful cheeses. Gruyère, white cheddar, or a blend of both would be delicious and add an extra nutty flavor.
• You can assemble the entire casserole up to a day in advance. Cover and refrigerate. You may need to add 10-15 minutes to the initial baking time when cooking from cold.
FAQ
Q: Can I make this potato and mushroom gratin vegan
A: Yes, you can easily adapt this recipe to be vegan. Use olive oil, substitute the heavy cream with full-fat coconut milk or a cashew cream, and replace the Parmesan with your favorite dairy-free shredded cheese or a sprinkle of nutritional yeast for a cheesy, nutty flavor.
Q: How can I add more protein to this vegetarian gratin
A: To boost the protein, you can layer in a cup of cooked white beans, like cannellini, between the potato layers. Serving the gratin alongside a simple green salad with chickpeas or a side of baked tofu would also create a more protein-rich vegetarian meal.
Q: What can I use instead of mushrooms in this recipe
A: If you’re not a fan of mushrooms, you can substitute them with other vegetables that sauté well. Try using a similar amount of chopped asparagus, wilted spinach (be sure to squeeze out all excess water), or even thinly sliced fennel for a different but equally delicious flavor profile.
Q: Is this gratin a good make-ahead vegetarian dish
A: Absolutely! This gratin is perfect for making ahead. You can assemble the entire casserole up to one day in advance, cover it tightly, and store it in the refrigerator. When you’re ready to bake, you may need to add 10-15 minutes to the initial 30-minute baking time since it will be cooking from cold.
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Creamy Potato, Mushroom, and Leek Gratin
Ingredients
Method
- Preheat your oven to 400°F / 200°C. Lightly grease a 1. 5-quart soufflé dish or casserole.
- In a medium saucepan, par-boil the potato slices in lightly salted water for 3 minutes. They will not be fully tender.
- Drain well and set aside.
- While the potatoes cook, heat 1 tablespoon (15 ml / 0.5 fl oz) of oil in a large skillet over medium heat.
- Add the mushrooms, leeks, garlic, rosemary, and salt.
- Sauté, stirring occasionally, until the leeks are tender.
- Stir the heavy cream into the skillet.
- Bring the mixture to a boil, then immediately reduce the heat and simmer gently for about 30 seconds, or until the sauce has slightly thickened.
- To assemble, arrange a third of the potato slices in the bottom of your prepared dish, overlapping them as needed. Spoon one-third of the leek mixture over the potatoes and sprinkle with 1/4 cup (960 ml) of the Parmesan cheese.
- Repeat the layers once more.
- Top with the remaining potatoes and the final third of the leek mixture.
- Drizzle with the remaining 1 tablespoon (15 ml / 0.5 fl oz) of oil.
- Bake, uncovered, for 30 minutes. Carefully remove from the oven and sprinkle the remaining 1/4 cup (960 ml) of Parmesan cheese over the top. Return to the oven and bake for an additional 5 to 10 minutes, until the potatoes are fork-tender and the top is golden and bubbly.
- Let the gratin stand for 10 minutes before serving to allow it to set.
- Serve warm, with a dollop of sour cream if you like.
