Braised Lamb Shank Shepherds Pie with Creamed Spinach

Name: Braised-Lamb Shank Shepherd's Pie with Creamed Spinach
Ingredients: 3 tablespoons vegetable oil; 5 1/2 pounds large lamb shanks (4 large); Salt and freshly ground black pepper; 2 small onions, sliced; 1/2 cup fresh thyme sprigs; 1/2 cup fresh rosemary sprigs; 1/2 cup dry white wine; 1 1/4 cups beef broth; 1 1/4 cups water; 3 pounds russet (baking) potatoes (about 6); 3/4 cup whole milk; Salt and pepper; 5 medium carrots, cut into 1/4-inch-thick slices; 3 tablespoons all-purpose flour; 3 tablespoons unsalted, softened butter plus 2 tablespoons melted; Creamed spinach, recipe follows; 1 package frozen creamed spinach; 2 tablespoons freshly grated Parmesan; 1/2 teaspoon salt; Pinch freshly grated nutmeg; Freshly ground black pepper