Potato gratin with Gruyere and Mushrooms
{serves 8-10}
1/4 c. olive oil
4 c. finely chopped leeks {white and pale green parts only..about 3 of them}
1 1/2 pounds mushrooms {such as shiitake, baby bella, crimini} slices and cubed into 1/2 inches. {about 10 cups}
2 garlic cloves, minced
3 pounds Yukon Gold potatoes, peeled, cut into 1/8-inch thick slices
2 c. heavy whipping cream
1 tsp salt
1/2 tsp freshly ground black pepper.
1 cup coarsely grated Gruyere cheese.