Cover letter: Full time Position where I interned

I am applying for a position at the office where I interned 2 years ago and am having trouble with my cover letter. I liked the work, I liked the people, I liked the hours, and they liked me (as evidenced by them requesting me from the intern list a 2nd year and recommending me for a conference).

My Question is this: How do I put that into a cover letter without it sounding like ``Hey, I know you, you know me. You already know I know your computer system and the work invovled. When do I start?´´

I know that at least the manager is still there and I'm reasonably sure at least half the same staff is as well.

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