Everyone loves to be first! Give each table at your event the chance to donate and win the opportunity to receive their dessert first.
To "play" this fun game: Each table at your event will receive an envelope or box where the people sitting at the table are invited insert cash (or check) bids. After all funds are collected (ie all bids are cast), collect the envelopes. The table whose envelope has the highest amount of cash wins the honor of being the first to "dash for their dessert."
This game can have many fun twists, with the 2nd and 3rd place winner gaining other honors at the events. Whatever the outcome, your nonprofit wins from the funds collected and the competition can be loads of fun.