Mold inside where the window meets the drywall.. obvious crack/leak somewhere in window.. how do I repair?

It really depends upon where the leak is occurring, as to what type of repair is required. Check the outside around the window to see if that's where the moisture is seeping in. Next check around the soffitt area to see if there's a place where water is entering. If you only repair the area where the mold is forming, you won't stop the moisture from coming in and causing subsequent damage.