Vegetable Shepherds Pie

Name: Vegetable Shepherd's Pie
Ingredients: 6 medium Yukon gold potatoes, peeled and diced; Kosher salt; 2 tablespoons extra-virgin olive oil; 1 large onion, diced; 3 large carrots, cut into 1/2-inch chunks; 2 stalks celery, cut into 1/2-inch chunks; 1 bunch baby turnips, halved or quartered if large; 6 cloves garlic, minced; Freshly ground pepper; 1/2 bunch fresh parsley, leaves chopped (stems reserved); 1 1/2 tablespoons Worcestershire sauce; 5 tablespoons unsalted butter; 3/4 cup chopped veggie burgers or vegetarian protein crumbles; 2/3 cup milk or half-and-half; Grated parmesan cheese, for sprinkling (optional)