Potato Gratin with Porcini Mushrooms & Mascarpone Cheese

Potato Gratin with Porcini Mushrooms & Mascarpone Cheese

by Amy Klein
adapted from Bon Appetit

4 ounces Marx Foods Dried Wild Porcini Mushrooms
1 cup boiling water
2 Tablespoons butter
2 Tablespoons vegetable oil
1/4 cup plus 2 Tablespoons grated Parmesan cheese
1 1/2 cups mascarpone cheese
1 cup whipping cream
3 garlic cloves, finely chopped
pinch of ground nutmeg
2 1/2 pounds of russet potatoes, peeled and cut crosswise in 1/8" slices

Place the mushrooms and boiling water into a medium bowl. Place a small bowl atop mushrooms to keep submerged. Let sit for 20 minutes. Drain and coarsely chop the mushrooms. 

Melt the butter with oil in a medium skillet over medium heat. Add the mushrooms and saute until they begin to brown. Sprinkle with salt & pepper. Remove from the heat. Whisk 1/4 cup Parmesan, mascarpone, whipping cream, garlic and nutmeg together; season with salt and pepper.  

Preheat oven to 325F. Butter a wide shallow 2 quart baking dish. Arrange 1/4 of the potato slices on the bottom of the dish. Sprinkle lightly with salt and pepper. Scatter 1/4 of the mushrooms over. Repeat potato slices and mushrooms. Spread half of the cheese mixture over. Repeat with remaining potatoes and mushrooms in two layers each. Top with the remaining cheese mixture. Sprinkle remaining 2 tablespoons of Parmesan cheese over the top.

Place the gratin dish on a baking sheet and bake uncovered until the top is brown and the sauce is bubbling; about 1 1/4 hours. Let stand 15 minutes before serving.