The real butter chicken is made from tandooried or pre grilled chicken. This is the most authentic I have found on you tube
Here are my tips:
1. Marinate your boneless breast pieces in garlic and lemon for 20 min, then marinate in spicey sauce, (up to you how much spice, you just use tandori mix) then grill/barbaque or stir fry it as you would on skewers. Here you are releasing the flovours, addin that grilled chichen look, givivg it that smoky taste, not cooking it fully.
2, Now make your butter chicken sauce be sure to fry the spices well (dont burn them!)then once you have added water tomatoes and milk /cream, simmer this well to thicken and you end up with a butter chicken sauce, to which you add your tandooried chicken, again simmer for at least 20min, then add cream, and serve with naan and rice.
Also some more secrets of indian cooking:
use authentic ingrediants from an indian shop
dont use too much spice mix, dont use too less. for 500gms meat use 11/1Tble of garam masala for spicy.
simmer on a low heat.
grind your onions seperatly, (garlic , ginger & fresh chili and a bit of oil all together), (almonds/cashew and tomatoes both together), seperatly in these groups in a blender prior to cooking to produce that lovely thickened sauce. And yes, you have to add them seperatly to the pot too!.
Hint fry onoins till just starting to color, and oil is frying around them
If using fresh tomatoes add extra honey/sugar to them and cook for a bit longer plus tomatoe paste (about a tablespoon per cup).