Wild Mushroom Shepherds Pie with Potato Chestnut Topping

Name: Wild Mushroom Shepherd’s Pie with Potato-Chestnut Topping
Ingredients: 3 pounds white mushrooms, coarsely chopped; 1 pound leeks, white and light green parts only, chopped; 1 carrot, chopped; 3 garlic cloves, crushed; 2 bay leaves; 1 1/2 tablespoon kosher salt; 1 tablespoon thyme leaves; 1 tablespoon black peppercorns; 1/2 teaspoon hot curry powder; 2 cups heavy cream; 6 tablespoons unsalted butter; 1/4 cup plus 2 tablespoons all-purpose flour