Prepare the Paneer: Combine cumin, coriander, cayenne, and salt in small bowl. Sprinkle both sides of the paneer with the spice mixture, pressing gently so it adheres. Set the paneer on plate, cover with plastic film, and refrigerate for 30 to 60 minutes. In a large bowl, whisk together the yogurt, ghee, garlic, and ginger. Cover and set aside so the flavors have a chance to blend.
Prepare the Sauce: Heat the ghee (or oil) in a large Dutch oven or heavy-bottom saucepan over medium heat until thin and shimmering. Add the onion and cook, stirring frequently, until lightly caramelized, 8-10 minutes. Add the garlic, ginger, pepper, tomato paste, and garam masala. Cook, stirring frequently, until fragrant, 1-3 minutes. Add the tomatoes, sugar, and salt, then bring to a boil. Reduce the heat to medium-low, cover, and simmer for 12-15 minutes, stirring occasionally. Stir in the cream and remove the pan from heat, covering to keep the sauce warm.
While the sauce is simmering, adjust an oven rack to the upper-middle position, then preheat the broiler. Line a baking sheet with foil. Dip the paneer into the yogurt mixture (the paneer should be coated with thick layer of sauce) and arrange on the prepared baking sheet. Discard any leftover yogurt. Broil until the paneer is hot and the exterior is lightly browning in spots, 10 to 12 minutes, flipping halfway through cooking. (Note: the time may vary depending on your oven’s broiler. You may want to use the “low broil” setting if your oven has one).
Remove the paneer from the oven and stir into the warm sauce. Add in the cilantro, adjust seasoning if needed, and serve with rice and/or naan.
Leftovers will keep in an airtight container the refrigerator for up to 5 days, or frozen for up to 3 months. (I add a splash of cream when reheating leftovers; the sauce thickens up slightly as it sits).
Ghee can be purchased in the international aisle at most grocery stores. It adds a ton of flavor to Indian cuisine. However, you can also use any neutral-flavored oil like vegetable, grapeseed, avocado, or canola oil.