How do I cutely ask my friend out who has been in love with me forever?

well does he know how you feel? I kinda went through the same situation with a girl, she told me she doesn't like me as a boyfriend. but I really really liked her. but after being shot down, my friends basically said either dump her, or test her. I just can't dump her, but the way guys will test if girls actually did have feelings for them is distancing themselves, so just try talking to him again first, and if he responds, than I think it means he still wants you. but that would be a really cute and creative way, your whole letter thing but I'm sure he's not pissed at you. maybe a little depressed if you did shoot him down recently

firstly - make sure you like him as most the time we girls like people we can't have e.g. now he's mad)
If he's liked you for two years purely give him a few hints and he would probably ask you out.
You say he wrote you a note, why don't you write him a note that would be cute
If your not really into that you could purely ask him to go for a walk to talk about "things" he will probably get the hint from that and then you don't even have to ask him "out" you could just say you really like him and things will take off from there.
Hope this helps.

firstly - make sure you like him as most the time we girls like people we can't have e.g. now he's mad)
If he's liked you for two years purely give him a few hints and he would probably ask you out.
You say he wrote you a note, why don't you write him a note that would be cute
If your not really into that you could purely ask him to go for a walk to talk about "things" he will probably get the hint from that and then you don't even have to ask him "out" you could just say you really like him and things will take off from there.
Hope this helps.