My engagment day conincides with my finace's birthday..need ideas to make it memorable birthday ever?

My Engagement is on 2nd july and my fiance has her bday on 3rd july. while we r in the midst of the engagement function, the clock will strike 12 and it wud b her bday. I want to make it most memorable for her. What can i do to impress her and flood her wid charm, love and affection.