How can I ask him to be my boyfriend?

I am crazy about this guy. He treats me so nicely and I feel respected and loved, I broke up w my toxic ex early this year and this new guy is exactly what I need. He called me his girlfriend a month ago (we have been talking since March but started going on dates in August) and I told him that I do like him but I wasn’t ready to be called a girlfriend. He understood since he knows my bad situation with my ex and was great about it. Now I decided that I really want to make it official but I need advice on how to ask him to be my boyfriend in a very romantic and cool way that he might like. Any ideas would be appreciated!!