In a large bowl, mix together the garlic, ginger, garam masala, turmeric, lemon juice and salt. Using a sharp knife make a couple of slashes across each of the chicken thighs, then place them in the bowl making sure to rub the marinade into each of the cuts.
Then add the yoghurt, mixing it in thoroughly cover and put in the fridge to marinate for an hour or overnight.
Pre-heat the oven to 230/450/gas mark 8. Place chicken thighs on a rack in a roasting tin, put on top shelf of the oven and toast for 15-20 minutes until the chicken is thoroughly cooked, turning the breasts over half way through the cooking time.
To make the spinach and cheese
Wash spinach in plenty cold water, letting any sand sink to the bottom, then rinse and drain well in a colander. Put in a large pan, cover with a lid and place on medium heat for 2-3 minutes. The spinach will cook in the steam made by the water left on its leaves. As soon as the leaves are wilted, remove the pan from the heat and drain, squeezing out as much liquid as possible then roughly chop.
Heat the oil in a sauce pan until hot, then add the cumin seeds and allow them to sizzle. Now add the onion and cook until it becomes translucent in colour. Add the garlic and continue to cook until the onions have softened. Stir the spinach into the mixture, continue to cook for a couple more minutes and then add the ricotta and vegetable stock.
Adjust the seasoning, pour on the cream, garnish with coriander and serve.