If you find your self in the same predicament this is a fun one day project that worked really well for me!
I gave each student a large peice of paper. On the back they had to write 4 ingredents you could buy at the grocery store but that you would not typically find in ice cream.
Examples: eggs, cucumbers, fish, raw meat, cheese, pasta, rice, donuts ect.
Then we switched papers around. So now each student had 4 ingredients they had to make into a four scoop ice cream cone. It produced a really fabulous "EWWW" "YUK" sound throughout the room.
(I modeled this with students before hand and talked about how we can add the ingredients chopped up inside the ice cream. I also brainstormed appropriate ingredients with students prior.)
Then we got to work making our Ice Cream.
WARNING: this project is not for those with week stomachs