Potato & Porcini Gratin

Potato & Porcini Gratin

Sides
Potatoes, Holidays

Serves 8

This is a truly luxurious dish that will be welcome at any festive occasion.

Ingredients #

  • 1 oz dried porcini mushrooms (about 1 cup)
  • 1 cup hot water
  • 5 large russet potatoes (about 3 lbs)
  • 3 garlic cloves, minced finely
  • 1 cup grated Gruyere cheese
  • ½ cup grated Parmeggiano Regiano
  • 1 tbsp butter, softened
  • 2 tbsp unsalted butter, frozen and cut into tiny bits
  • 2 cups milk
  • 1 cup heavy cream
  • 2 tbsp minced fresh chives

Instructions #

In a bowl, soak the porcini in the hot water for 30 minutes or until softened. Strain the soaking liquid through a fine sieve lined with a coffee filter into a small saucepan. (Do this carefully — there will be grit in the soaking liquid). Boil the strained liquid until reduced to a scant half-cup.

Preheat oven to 350 F.

Rinse the porcini carefully under cold water to remove any remaining grit. Pat dry and chop coarsely. Peel the potatoes and slice 1/8 inch thick.

Heat the 1 tbsp of soft butter in a saucepan over moderate heat. Add the porcini and garlic and sautee, stirring, for 2 minutes. Scrape into a small bowl and set aside to cool.

Toss the grated cheeses together.

Butter a 2-quart gratin dish.

Arrange a layer of potato slices, overlapping slightly. Very lightly season with salt and pepper. Sprinkle a small amount of the porcini mixture over the potatoes, and sprinkle a pinch of the cheese mixture over that (just enough to help bind the layers, this shouldn’t be “cheesy”). Repeat these layers until the potatoes are used up. You should finish with a layer of potatoes with the last of the porcini mixture scattered over the top. Reserve enough cheese mixture to produce a nice brown top (at least a few tablespoons).

In a saucepan, combine the porcini liquid, the milk, the cream, a tablespoon of the chives, and salt and pepper to taste (keeping in mind that you’ve already salted the potato layers, and that the cheeses are salty too). Bring the liquid to a boil and pour gently over the gratin.

Sprinkle the remaining cheese evenly over the top of the gratin. Bake until the potatoes are tender throughout (about 1 hour). Remove from the oven and allow to sit for 20 minutes. Sprinkle the remaining chives and serve.