Recipe: Mixed Mushroom and Goat Cheese Popover Bake

Name: Recipe: Mixed Mushroom and Goat Cheese Popover Bake
Ingredients: 2 tablespoons olive oil, plus more for coating the pan; 1 medium red onion, halved and thinly sliced; 1 pound mixed fresh mushrooms, such as cremini, shiitake, or portobello, cleaned and sliced (about 5 cups); 2 cloves garlic, minced; 2 teaspoons chopped fresh thyme leaves; Kosher salt; Freshly ground black pepper; 4 ounces goat cheese, crumbled (about 1 cup); 1 cup whole or 2% milk; 2 large eggs; 3 tablespoons melted unsalted butter, divided; 1 cup (5 ounces) all-purpose flour; 1/4 teaspoon kosher salt