Shepherd's Pie

1. Cook the lamb in a large Dutch oven over medium-high heat, breaking the meat into small pieces with a wooden spoon, until the meat is no longer pink and the fat has rendered, about 5 minutes. Drain the lamb through a fine-mesh strainer, reserving the drippings.

2. Return 2 T of the reserved lamb drippings to the pot and heat over medium-low heat until shimmering. Add the onions and 1 tsp salt and cook until softened and lightly browned, 5 to 7 minutes. Stir in the garlic and tomato paste and cook until fragrant, about 30 seconds. Stir in the flour and cook, whisking constantly, until incorporated, about 1 minute. Whisk in the broth and wine, scraping up any browned bits. Stir in the drained lamb, thyme, Worcestershire sauce, and rosemary and cook until the mixture begins to thicken, about 2 minutes. Off the heat, stir in the peas and carrots and season with salt and pepper to taste. Transfer the mixture into a 13 by 9 inch casserole dish; set aside.

3. Meanwhile, place the potatoes in a large Dutch oven and cover by 1 inch of water. Bring to a boil over high heat, then reduce to a simmer and cook until the potatoes are tender, about 20 minutes. Drain the potatoes, return them to the pot set over low heat, and mash to a smooth consistency. Stir in the cream, followed by the butter. Season with salt and pepper to taste.

4. With a large spoon, dollop the mashed potatoes over the lamb filling. Using a rubber spatula, smooth the potatoes out into an even layer and push to the edges of the baking dish.

5. TO STORE: Wrap the dish tightly with plastic wrap that has been sprayed with vegetable oil spray and then foil and refrigerate for up to 2 days or freeze for up to 1 month. (If frozen, the casserole must be thawed completely in the refrigerator, about 24 hours, before baking.)

6. TO SERVE: Adjust an oven rack to the middle position and heat the oven to 400 degrees. Unwrap the dish and place the casserole on a foil-lined rimmed baking sheet. Bake until the sauce is bubbling and the top is browned, about 1 hour.

7. TO SERVE RIGHT AWAY: Bake as directed in step 6, reducing the baking time to 35 minutes.