I just asked what is the best way to resign in an honourable manor.
Have a chat, tell him what you're thinking, give him a chance to change your mind. If he doesn't, let him know he hasn't, and why, then hand in your formal resignation letter.
After that, your resignation letter then doesn't have to say too much: "With regret, I have taken the decision to resign from company x with effect from xx/xx/xxxx. I appreciate the opportunities offered me, … learnt a great deal… but feel that I need to explore direction y… will finish my projects over notice period…"
Pretty much what I did on Monday!
Good luck,
Ed