I make chicken tikka on and off and I normally marinade the meat for over 24 hours every time I do it. I notice that, after grilling the chicken it still has a cake-like coating. I have noticed this regardless of whether I use yogurt in my marinade or not. Is there anything I could do to get more of a drier, less cakey coating in the end product?
Use a higher chicken-to-marinade ratio, so a small amount of chicken isn't sitting in masses of marinade. If you see chicken tikka marinading in a restaurant, you'll note that is only lightly coated.
Failing 1., simply wipe off the excess marinade before cooking.
Grill on high heat. The marinate, together with the fat, will form a delicious crust, something special indeed. If heat is not high, it will not chat, but become soft and gooey.
I think it is due the marination you are using to cook the chicken pieces. You should use a balanced and simple marination. Use a little more oil in the marination,it will help to roast the coating properly. Oil play an important part while cooking Tikka or kebabs. It not only help to cook properly but also keep them moist. If you like you can check the recipe of tandoori masala used in restaurants for chicken Tikka or kebabs. Restaurant style Tandoori masala