Caramelized Onions
3 tablespoons olive oil
2 pounds (about 6 medium) onions, thinly sliced crosswise into rounds
1 teaspoon kosher salt
Smashed Potatoes
3 pounds all-purpose potatoes, such as Yukon Gold, scrubbed but not peeled and cut into 2-inch (5-cm) chunks
4 garlic cloves, smashed with the flat side of a knife
1 teaspoon kosher salt, plus more to taste
4 tablespoons unsalted butter (2 oz), cut into 4 pieces
Filling
1 tablespoon olive oil
3 medium (about 1 1/2 cups) carrots, scrubbed or peeled and finely diced
2 pounds ground lamb (or ground beef)
1 1/2 teaspoons minced fresh thyme leaves
1 teaspoon kosher salt
2 tablespoons all-purpose flour
1 tablespoon store-bought or homemade tomato paste (ketchup will do in a pinch)
2 cups homemade chicken stock or low-sodium canned chicken broth
1 cup grated Cheddar (3 1/2 oz)
Caramelize the Onions
In a large, heavy-bottomed skillet over medium heat, warm the oil until hot. Add the onions to the pan and turn the heat down to medium-low.
Sprinkle the onions with the salt and cook, stirring frequently to make sure they brown evenly, for about 40 minutes, or even longer, until they’re completely softened and golden brown. This will take time, so don’t rush. You should have about 1 1/2 to 2 cups of onions. (You can cover and stash them in the fridge for up to 1 week.)
Steam (or Boil) the Potatoes
Find a large pot that’s large enough to accommodate a steamer insert or heatproof colander that will hold your potatoes. Pour enough water into the pot to reach the bottom of the steamer or colander, add the potatoes and garlic, and sprinkle with the salt. Cover the pot and bring the water to a boil.
Reduce the heat to maintain an active simmer and steam the potatoes, until they break apart easily when poked with a fork, 25 to 30 minutes.
Remove the potatoes and garlic from the steamer, carefully pour off any remaining hot water in the pot, and return the potatoes and garlic to the pot. Place over low heat, shaking the pan occasionally to toss the potatoes and garlic, until any excess water in the potatoes has evaporated, maybe 30 to 60 seconds.
Add the butter to the pot and use a potato masher to mash the potatoes and garlic until blended but not completely smooth. Adjust seasoning to taste. (You can cover and stash the mashed potatoes in the fridge for up to 24 hours.)
Make the Filling
Crank the oven to 400°F (200°C).
In a large skillet over medium-high heat, warm the oil until hot. Add the carrots and cook, stirring occasionally, until softened, 5 to 7 minutes.
Add the lamb (or beef), thyme, and salt, and sear, stirring occasionally and crumbling the meat into small crumbles, until the meat is no longer pink, about 10 minutes. Carefully pour off all the fat.
Sprinkle the flour over the lamb and cook, stirring, for 1 minute. Then stir in the tomato paste and continue cooking and stirring, for 2 minutes more. Add the stock and 1 cup of the caramelized onions, increase the heat slightly, and simmer until the liquid thickens slightly, about 2 minutes.
Assemble & Bake
Spread the lamb in a shallow round or oval 3-quart casserole or a 9-by-13-inch baking dish. Spread the potatoes on top. Strew the remaining caramelized onions over the mashed potatoes and then sprinkle with the Cheddar.
Bake the shepherd’s pie until the Cheddar is golden and crusty, about 20 minutes. Let cool slightly before serving it straight from the dish. Originally published October 19, 2017.