Low FODMAP Potato Cheese Gratin with Mushrooms

Name: Low FODMAP Potato Cheese Gratin with Mushrooms
Prep time: 15 min
Cook time: 40 min
Total time: 55 min
Cuisine: American
Ingredients: 3 tablespoons Garlic-Infused Oil, (made with olive oil, or purchased equivalent, divided); 6- ounces (170 g) cleaned oyster mushrooms, chopped; 2 pounds (910 g) yukon gold potatoes, peeled; 3 cups (720 ml) lactose-free half-and-half, (at room temperature); 1 teaspoon kosher salt; Freshly ground black pepper; 1/4 pound (115 g) Gruyere cheese, (grated)