If you are serious...
then sautee onions and tomatoes in a little oil, ginger, garlic, dhaniya powder, jeera powder, any green seasonings (little oregano, khasturi methi, dhaniya...something fresh smelling/tasting really) solid jeera, red chilli, chopped green chillis if you like it spicy, salt, little sugar, cashews. grind it up in a mixer once its cooked till it becomes a smooth paste
for healthy butter chicken, loosen the thick paste with water and milk. for unhealthy - loosen the paste with water, half and half or cream, and a big slab of butter.
for healthy chicken - bake it till its cooked on the outside ONLY in a light masala (garlic paste, ginger paste, red chilli, dhaniya and jeera powder, whatever you like really or even tandoori powder, lemons)
for unhealthy chicken - sautee it in a light masala to cook outside oNLY
dump chicken in the gravy and let it cook thoroughly...by cookin the inside of the chicken in the gravy..it will still be juicy.
u can add ketchup for tangyness. U can add ilaichi also just make sure you put it in the mixer with the rest of the masala so no solid pieces are left. add food coloring if u want a better color too.
ok bye
PS - if u want more help, google it im sure you will find ton of websites with recipes
Pavan