Heat the oil in a pressure cooker and fry the cinnamon, bay leaves, cardamom pods and cloves for a minute. Add the finely chopped onion, ginger and garlic and fry for 5 minutes. Add the lamb cubes, chopped spinach, red chili powder, coriander powder, cumin powder, salt and 2 cups of water. Cover the lid and cook under high pressure for 5 minutes. Lower the heat and cook for 20 more minutes with the lid closed. Release the pressure immediately using quick release method by keeping the pressure cooker under the running cold water with lid on. Then uncover and add the garam masala and mix well. Bring this to a boil with lid open. Cook for 10 more minutes until the gravy is thick. Serve hot.