To make the kofta's, place all the ingredients in a medium-sized bowl and bring together with your hands until firm.
Roll into 8 balls of equal size.
Place on a baking tray and bake in a pre-heated oven at 190 degrees (170 degrees fan oven) for 25 minutes, turning once.
In the meantime make the sauce by placing the onion in a large pan with a little oil and water. Cook over a low heat with the lid on until translucent but not brown. Add more water if it becomes dry and starts to brown.
Allow the water to evaporate, then add the garlic and ginger and continue to cook for a further minute.
In a separate pan, dry fry the cumin seeds, chilli powder, coriander and tumeric over a medium heat for a minute or so until you hear the cumin seeds pop.
Add the passata, water, dry fried spices, cardamon pods, cashew nut cream or butter and salt to taste and simmer over a low heat for a further 10-15 minutes. Add more water if the sauce becomes too dry.
At the end of the cooking time add the single cream and stir until heated through.
To serve, place the sauce in a bowl and add the cooked koftas. Scatter over some chopped coriander and cashew nuts and serve with rice and papadums (checking that they are gluten-free!).