Heat 3 tablespoons oil in a frying pan, add the chopped onions, bay leaf and mushrooms, cook for 2 minutes over a medium-high heat. Add the keema and cook for 5 minutes. Add the tomato puree, mix then add the chilli powder, Tabasco and the paprika. Now add the chopped tomatoes, kidney beans and water. Season well with salt and pepper to taste. Allow to reduce on low heat for 20 minutes.
In a deep, round baking dish, place a couple of spoonfuls of the chilli into the bottom of the dish (don't put too much it has to go a long way!). Now put a chapati on top and spread a tablespoon of the soured cream over the it. Now add another couple of spoonfuls of the chilli and top with another chapati, then another tablespoon of the soured cream; keep repeating this process until you run out of chilli or space. The final thing at the top should be a chapati by itself (with no chilli on top). Spread the remaining soured cream over the top (this should be quite a thick layer).
Sprinkle with paprika and bake in the oven on the middle/top shelf for 30 minutes or until bubbling all the way through.