Potato and mushroom gratin

Who says a gratin needs to have cheese?  This dish, from the Liguria region of Italy, is delicious in its purity: basically just potatoes, mushrooms, garlic and herbs.  Be sure to use a very high quality extra virgin olive oil here, because it really makes a difference.  I used a dark green unfiltered oil from Spain and the flavor was phenomenal. It was by far the biggest hit of last weekend’s Sunday Night Supper Club.

Ligurian Potato and Mushroom Gratin

4 tablespoons extra virgin olive oil, divided
1 ¼  pounds Portobello mushrooms, gills scraped off, halved and thinly sliced
4 cloves garlic, minced
2 pounds Yukon Gold potatoes, peeled and very thinly sliced (a mandolin is kind of essential)
¼ cup chopped flat leaf parsley
1 teaspoon fresh thyme
½ teaspoon chopped fresh rosemary
Salt and freshly ground black pepper to taste

Preheat the oven to 375 degrees. Heat 2 T. oil in a large skillet.  Add the mushrooms and cook for 5 minutes. Add garlic and cook 2 minutes more, until mushrooms are tender.

Mix the potatoes with the remaining oil and the herbs, and season with salt and pepper. Place a third of the potatoes in an oiled gratin dish or 8×8” square ceramic baking dish. Top with half of the mushrooms, removing them from the skillet with a slotted spoon. Repeat layers, ending in potatoes.  Pour any liquid from the skillet on top.

Cover tightly with foil and bake for 45 minutes. Uncover and bake an additional 20 minutes.

Serves 6