Though I have tried the recipe exactly as written above (including making the tandoori masala powder from scratch) you can also used store-bought tandoori powder and follow the box directions for marination. The end result is delicious either way.
Where the above recipe totally shines is the baking part - cook exactly as per the direction given and you will be looking at juicy, professional looking and tasting tandoori chicken in the end.
The following mint sauce recipe makes a great dip for the tandoori chicken:
I followed the directions exactly - only added a wee bit more garlic (I like garlic) and half a green chilly.