Pot Pie Chicken Thighs

Name: Pot Pie Chicken Thighs
Ingredients: 4 bone-in skin-on chicken thighs, trimmed and patted dry (about 1 1/2 pounds); Kosher salt and freshly ground black pepper; 2 tablespoons extra-virgin olive oil; 2 medium carrots, cut into 1-inch pieces; 3 stalks celery, cut into 1-inch pieces; 8 ounces cremini mushrooms, quartered; 1 medium Yukon gold potato, peeled and cut into 1-inch pieces; 4 ounces (about 1 1/4 cups) frozen pearl onions; 1 1/2 tablespoons unbleached all-purpose flour; 2 teaspoons reduced-sodium chicken bouillon paste; 1/2 cup whole milk; 1 dried bay leaf; 2 sprigs fresh thyme