Decadent Potato Gratin with Porcini Mushrooms and Mascarpone

Ingredients

Localized ingredient list prepared for quick scanning.

• 4 ounces dried porcini mushrooms
• 1 cup boiling water
• 2 tablespoons butter
• 2 tablespoons extra virgin olive oil
• 1/4 cup parmesan cheese, grated
• 2 tablespoons grated parmesan cheese
• 1 1/2 cups mascarpone cheese
• 1 cup whipping cream
• 3 garlic cloves, chopped
• 1 pinch freshly grated nutmeg
• 2 1/2 lbs russet potatoes, peeled and sliced 1/8-inch thick

Method

Follow the steps in order for the best result.

1. In a medium bowl, combine the dried porcini mushrooms with 1 cup of boiling water. Submerge the mushrooms using a small bowl placed on top to keep them weighed down. Allow the mushrooms to soak for 20 minutes. After soaking, drain the mushrooms and chop them coarsely.
2. In a medium skillet, melt the butter together with the olive oil over medium heat. Add the chopped mushrooms and sauté until they begin to brown, approximately 3 minutes. Season with salt and pepper, then remove from heat.
3. In a separate small bowl, whisk together 1/4 cup of grated Parmesan cheese, the mascarpone cheese, whipping cream, chopped garlic, and nutmeg. Season the mixture with salt and pepper to taste.
4. This is a good point to prepare the mushrooms and cheese mixture up to a day in advance. Simply cover them separately and store in the refrigerator until needed.
5. Preheat your oven to 325°F (160°C). Butter a wide, shallow 2-quart baking dish.
6. Arrange one-fourth of the potato slices in the bottom of the prepared baking dish. Sprinkle lightly with salt and pepper. Scatter one-fourth of the sautéed mushrooms over the potatoes. Repeat this layering process.
7. Spread half of the cheese mixture evenly over the potato and mushroom layers, shaking the dish gently to help the mixture settle.
8. Repeat the layering process with the remaining potatoes and mushrooms in two more layers each. Spread the remaining cheese mixture over the top layer.
9. Sprinkle the remaining 2 tablespoons of grated Parmesan cheese evenly over the top of the gratin.
10. Place the gratin dish on a rimmed baking sheet to catch any potential spills during baking.
11. Bake the gratin in the preheated oven until the top is golden brown and the sauce is bubbling around the edges, approximately 1 hour and 15 minutes.
12. Allow the gratin to rest for 15 minutes before serving. This allows the sauce to thicken slightly and the flavors to meld together.
13. The gratin can be prepared up to 2 hours ahead of time. Let it stand at room temperature, then tent loosely with foil and rewarm in a 300°F (150°C) oven for about 20 minutes before serving.