Creamy Mushroom and Potato Gratin

• 6 tablespoons butter
• 1 1/2 pounds fresh button mushrooms, sliced
• 1 1/2 pounds fresh crimini mushrooms, sliced
• 3 tablespoons minced garlic
• 2 teaspoons dried thyme
• 1 teaspoon dried rosemary, crushed
• 2 cups chicken broth
• 1 1/2 teaspoons salt, divided
• 1 1/4 teaspoons freshly ground black pepper, divided
• 3 pounds Yukon Gold potatoes, peeled and thinly sliced
• 2 cups Parmesan cheese
• 2 cups half-and-half or light cream
• 2 cups heavy whipping cream

Preheat oven to 375 degrees. Grease a 13x9-inch baking dish and set aside. Melt butter in a large pot over medium-high heat. Saute mushrooms in butter until liquid evaporates, about 5-10 minutes. Stir in garlic, thyme and rosemary, then cook 1 minute. Pour in chicken broth and cook until liquid evaporates. Season with 1/2 tsp of the salt and 1/4 tsp of the pepper. Arrange 1/3 of the potatoes in prepared dish, overlapping slightly. Spread 1/2 of the mushroom mixture evenly over potatoes, then sprinkle 1/3 of the cheese over mushrooms. Repeat layering, then arrange remaining potatoes on top. In a large bowl, mix together half and half, heavy cream, remaining salt, and remaining pepper. Pour mixture over potatoes, cover loosely with foil, and place baking dish on middle rack in oven. Bake until potatoes are tender, about 1 hour and 15 minutes. Uncover and sprinkle the remaining cheese over potatoes. Bake until cheese melts, about 10-15 minutes longer.

Two kinds of mushrooms and lots of flavorful herbs make this an ideal side dish to bring to a holiday gathering. It pairs nicely with turkey and ham, and fits nicely with a formal or down-home meal.