Wash and clean the chicken. Cut into 1-2 inch equal-sized pieces and set aside
Wash the spinach thoroughly. Boil water in a stockpot. Add 1 tablespoon salt to boiling water and add the spinach and cook for 2-3 minutes
Strain the spinach and refresh with cold water to stop cooking any further
Blend the spinach in a blender along with green chillies. Set aside
Heat oil and butter in a frypan or kadhai. Add onions and fry until it is golden brown
Add ginger, garlic and fry for a further 1-2 minutes
Add salt and tomato puree. Cook until the tomatoes are done and oil separates. Add coriander powder, cumin powder, red chilli powder, turmeric powder and saute on low flame for few minutes taking care not to burn the spices. Add ½ cup water to adjust consistency if needed
Add the chicken pieces and mix well. Cover and simmer on low flame until the chicken is almost cooked.
Add the spinach puree and mix well. Simmer for another 5 minutes
Add the garam masala and mix well. Turn off the heat and squeeze in the juice of half a lemon and mix. Optionally, you may also add a dash of cream.