POTATO MUSHROOM GRATIN

By gaster16

Ingredients

• 5 tablespoons olive oil, divided
• 2-1/2 lbs. potatoes, peeled, cut lengthwise into 1/8" thick slices
• 1-1/2 teaspoons coarse kosher salt plus additional for mushrooms
• 3/4 teaspoon freshly ground black pepper plus additional for mushrooms
• 1-1/4 cups (or more) heavy whipping cream, divided
• 1 cup freshly grated Parmesan cheese (about 3 ounces), divided
• 2 tablespoons chopped fresh thyme
• 6 garlic cloves, thinly sliced
• 12 ounces fresh crimini mushrooms, sliced

Preparation

Step 1

Preheat oven to 375 degrees. Brush 13x9x2" glass or oval ceramic baking dish with 2 tablespoons oil. Arrange 1/3 of potatoes, slightly overlapping, in dish. Sprinkle with 1/2 teaspoon coarse salt and 1/4 teaspoon pepper. Pour 1/3 cup cream over, sprinkle with 1/4 cup cheese. Repeat layering of the above measurements 2 more times. Bake uncovered until potatoes are tender, adding cream by tablespoonfuls if dry, about 45 minutes. Remove from oven, maintain oven temperature.

Sprinkle thyme and garlic slices over gratin. Toss mushrooms in medium bowl with 3 tablespoons oil, sprinkle with coarse salt and pepper. Arrange mushroom slices atop gratin around edge of dish. Drizzle with 1/4 cup cream, sprinkle with 1/4 cup cheese. Continue to bake uncovered until mushrooms are tender and potato edges are golden brown, about 20 minutes longer.