Simply replace the unfilled areas such as "" and "[date]" with your information.
I thought I might write you to tell you that I had a fantastic time [day] night. I can't remember a time when I had a more enjoyable conversation with someone. It was so easy to open up to you, as if being with you was the most natural thing in the world.
You have so many wonderful attributes that it would be hard for me to point out which attracts me the most. You are [adjective], [beautiful/ handsome], and [additional adjective]. I look forward to getting to know you better.
[Name], I hope you have a wonderful [day/week]. I can't wait to see you again. I look forward to hearing from you.