Instructions

1. Peel and halve 2 pounds medium or large Yukon Gold potatoes. Place in a large saucepan and add enough cold water to cover and 1 tablespoon of the kosher salt. Bring to a boil over high heat. Meanwhile, place 1 tablespoon garam masala, 2 teaspoons Kashmiri chili powder, and 1 1/2 teaspoons of the ground turmeric in a small bowl.
2. Reduce the heat to medium and gently simmer until the potatoes are cooked through and knife tender, 15 to 20 minutes. Meanwhile, dice 2 medium white or yellow onions (about 3 cups) and peel and mince 1 (2-inch) piece ginger until you have 2 tablespoons; place both in a medium bowl. Mince 5 garlic cloves (about 1 heaped tablespoon) and 1 to 2 serrano chiles (1 to 2 tablespoons), and place both in a small bowl.
3. Drain and return the potatoes to the pot. Cover and keep warm.
4. Arrange a rack in the middle of the oven and heat the oven to 400°F. Heat 3 tablespoons canola oil in a large, high-sided, oven-safe 12-inch regular or cast iron skillet over medium heat until shimmering. (Alternatively, use a Dutch oven or large frying pan for the filling, then transfer to a 9x13-inch baking dish for baking.) Add the onion mixture and 1/2 teaspoon of the kosher salt. Cook, stirring occasionally, until the onions soften and start to turn golden around the edges, 8 to 12 minutes.
5. Add the garlic mixture and 1/4 cup tomato paste. Cook, stirring frequently, until the tomato paste turns a shade darker, 2 to 3 minutes. Add the garam masala mixture and cook for 30 seconds to bloom the spices.
6. Add 2 pounds lean ground beef and 1 teaspoon of the kosher salt. Stir to combine with the onion mixture. Increase the heat to medium high and continue to cook, breaking the meat up into crumbles, until the meat starts to lose some of its pink color, 3 to 5 minutes.
7. Add 1 1/2 cups water, stir to combine, and bring to a simmer. Cover and reduce the heat to medium low. Simmer until the meat is cooked through and a thick gravy starts to form and some of the fat from the beef starts to pool on the surface of the sauce (this is a sign of good keema!), 20 to 25 minutes. Meanwhile, coarsely chop the leaves and tender stems of 1/3 medium bunch fresh cilantro until you have 1/2 cup. Finish the potatoes.
8. Pass the potatoes through a ricer into a medium bowl, or transfer into a medium bowl and mash with a potato masher or fork into your desired consistency. Place 3/4 cup whole milk and the remaining 1/2 teaspoon kosher salt in the now-empty pot. Heat over medium heat until the milk is hot and just coming to a simmer.
9. Add the remaining 1 teaspoon ground turmeric, 1/4 teaspoon of the black pepper, and 2 tablespoons of the unsalted butter. Stir until the turmeric dissolves into the milk, about 1 minute. Pour over the potatoes and fold mixture together until fully incorporated. Taste and season with kosher salt as needed.
10. When the keema is ready, if there are any big clumps of meat remaining, break them up into smaller pieces. Turn off the heat. Add 1 1/2 cups frozen peas and the cilantro and stir to combine. Taste and season with more kosher salt as needed. (Transfer to a 9x13-inch baking dish at this point if not using a 12-inch high-sided skillet.)
11. Dollop the turmeric mashed potatoes on top of the keema and then spread the potatoes into an even layer, making sure as little sauce is showing as possible. Drag the tines of a fork across the surface in one direction, rotate the pan 90 degrees, and run the fork across the surface again to create a small diamond pattern.
12. Cut the remaining 2 tablespoons unsalted butter into 8 pieces and scatter over the potatoes. Sprinkle with the remaining 1/4 teaspoon black pepper.
13. If using a skillet, place on a rimmed baking sheet (skip if using a baking dish). Bake until golden-brown on top and the sauce is bubbling, about 25 minutes. If you want extra golden-brown potatoes, finish under the broiler for 3 to 5 minutes. Let cool for 5 minutes. Serve out of the skillet with plain yogurt on the side.