Prepare the kofta spinach first, because it must be as dry as possible: blanch the leaves in boiling water for 2 minutes, drain into a sieve and press under cold water to stop the cooking. Then squeeze handful by handful, hard, until almost no water comes out, and chop the squeezed spinach finely. Wet spinach is the one thing that ruins these koftas, so take your time over this step.

Tip the chopped spinach into a wide bowl with the mashed potato, roasted besan, ginger-green chilli paste, garam masala, turmeric and salt. Mix and knead lightly into a soft, pliable dough — it should hold together when squeezed without sticking wetly to your fingers. If it feels loose, work in another spoonful of besan; if it is stiff, a teaspoon of the spinach water will loosen it. Rest the mixture for 5 minutes, then divide and roll into about 12 smooth balls, roughly the size of a lime, with lightly greased palms.

Heat oil for deep frying in a kadai on medium heat — a small pinch of the mixture dropped in should sizzle, rise and turn golden steadily rather than browning at once. Fry the koftas in batches, turning them gently, until they are an even deep golden and crisp all over, about 4 to 5 minutes a batch. Drain on kitchen paper. Fry one and taste it for salt before you commit the whole batch.

For the gravy, blanch the second lot of spinach the same way, then blend it to a smooth puree with a splash of its blanching water. Keep the lid off the blanching pan and do not overcook the leaves — two minutes is enough — or the puree will dull to an olive colour instead of staying vividly green.

Heat the oil (and butter or ghee, if using) in a pan and add the cumin seeds. When they sizzle and darken a shade, add the onion paste and fry on medium heat for 7 to 8 minutes, stirring often, until it turns golden and loses its raw smell. Stir in the ginger-garlic paste and fry for another minute.

Pour in the tomato puree with the coriander powder, red chilli powder and salt. Cook this masala down for 6 to 8 minutes, stirring and scraping, until it thickens, darkens slightly and oil begins to glisten at the edges — this cooked-down base is what stops the finished gravy tasting thin and raw.

Stir in the spinach puree and about 3/4 cup of water, and simmer gently for 4 to 5 minutes — just long enough for the raw edge of the puree to cook off and the gravy to come together at a pouring, coating consistency. Finish with the garam masala, the crushed kasuri methi and the cream, and simmer for 1 final minute. Taste and adjust the salt.

Add the koftas only when you are ready to eat: either lower them into the hot gravy and simmer for barely 2 minutes so they warm through while keeping their crust, or arrange them in the serving dish and pour the gravy over. Swirl a little extra cream on top, scatter over a few ginger juliennes if you have them, and serve at once with naan, roti or jeera rice.