Boil the potato for kofta until tender, then drain in colander and allow to cool.
Meanwhile, heat oil over medium-low heat and cook onions until very soft and deep golden brown (don't rush this step, it's important for the flavour). Add ginger and garlic, and cook 1-2 minutes, until fragrant.
Stir in salt, cumin, coriander, cayenne, cinnamon and cardamom pods and cook a minute more. Add tomato puree, nut butter and water; cook until oil starts to bubble up and shimmer on top.
Stir in cream and sugar; simmer, covered, about 10 minutes then turn off the heat and let stand while you finish making the koftas.
To Make Kofta
Grate or crumble the paneer into a large bowl. Add remaining ingredients and stir well to ensure even distribution. Form into golfball-sized balls (you'll get about 12). Use oiled hands if the mixture is sticky, and place them in the freezer for 10 minutes if very soft.
Heat a few tablespoons of oil in a nonstick or cast iron pan over medium-high heat. Add koftas in a single layer with enough space between each to easily be able to slide a spatula under them for flipping. You might have to work in batches. Brown the koftas on the underside until they lift easily with a spatula, then flip and brown on the other side. Transfer koftas to paper towel-lined plate, and proceed with the next batch.
Over low heat, bring the sauce back up to a gentle simmer. Taste and add salt, if needed, then slide the fried koftas in and gently stir to coat. Top with cilantro.