Make the Best Shepherd's Pie Recipe: rich meat gravy topped with creamy garlic mash. Bake until golden for a cozy one-dish dinner.
Peel and quarter the Russet potatoes and place them into a large pot of salted water. Bring to a boil and cook until a knife slides in easily; keep them simmering while you move through the next steps so the potatoes finish while the filling comes together.
In a large skillet, melt the butter over medium-high heat and add the chopped onion. Sauté the onion until soft and translucent, about five minutes, stirring occasionally so it browns gently and becomes sweet and glossy.
Add the lean ground beef (or lamb) to the skillet with the softened onions and cook over medium-high heat, breaking the meat up as you go, until it is just browned and no longer pink—about six to eight minutes. Let the meat develop small caramelized bits for deeper savory flavor.
Reduce the heat to medium and stir in the Italian seasoning, tomato paste, and flour. Cook for about a minute, stirring constantly, so the flour loses its raw taste and the tomato paste darkens and blends into the meat for a concentrated savory base.
Pour in the beef broth and add the Worcestershire sauce and salt, scraping up the fond from the bottom of the pan. Allow the liquid to reduce and thicken slightly until the filling is a glossy, clingy gravy that will hold the vegetables and potatoes together.
Stir the frozen mixed vegetables into the thickened meat gravy and cook for about five minutes, stirring often, until the vegetables are warmed through and tender but still hold their color and shape—bright peas, corn, and diced carrots suspended in a rich meaty sauce.
When the potatoes are nearly done, warm the heavy cream with the butter, minced garlic, salt and pepper in a small saucepan until the butter melts and the mixture is hot and aromatic—do not boil. This creates a silky, fragrant liquid that will loosen the potatoes for a smooth mash.
Drain the potatoes and return them to the pot. Pour the warmed cream-butter-garlic mixture over the potatoes and mash vigorously until the topping is smooth, creamy, and seasoned—no large lumps, just a pillowy texture that holds soft peaks when raked with a fork.
Transfer the hot meat-and-vegetable mixture into a 9×13 rectangular casserole dish, spreading it into an even layer. Spoon or pipe the mashed potatoes over the meat, then smooth with a rubber spatula and rake a fork across the surface to create textured ridges that will brown in the oven. Leave the assembled, unbaked pie on the surface while the oven preheats and you prepare to bake.

Bake the assembled casserole uncovered at 375°F until hot and bubbly, about 30 minutes, then move the dish briefly under the broiler for a few minutes to develop a golden, slightly crisp crust—watch it carefully so the ridges brown without burning.
Let the baked shepherd’s pie sit for a few minutes so the filling sets, then sprinkle with chopped fresh parsley if desired. Serve directly from the rectangular casserole with a spoon resting in the dish, the gravy thick and glossy and the potato top golden and textured.
