Shepherds Pie

Name: Shepherd's Pie
Ingredients: 1/4 cup unsalted butter; 1 pound chopped lamb shoulder or lamb fillet; 1 cup chopped yellow onions; 2 carrots, chopped; 1 1/2 teaspoons salt; 1 teaspoon ground black pepper; 4 ounces button mushrooms, wiped clean and sliced; 1 bay leaf; 2 tablespoons all-purpose flour; 1 tablespoon tomato paste; 1 1/4 cups lamb or beef stock; 1 teaspoon Worcestershire sauce; 1 pound potatoes; 1/8 teaspoon ground nutmeg; 1/2 cup heavy cream; 1/2 cup white cheddar, grated