A quick and easy snack/treat that you can customize for any time of year is MARSHMALLOWS. I just made a batch for my girls' Halloween party at school. Take some Popsicle sticks and place them in the marshmallows. Melt some chocolate. I used white chocolate chips and added food coloring to make them orange for pumpkins, green for Frankenstein, etc. You can use any color.
Anyhow, you just dip the marshmallows in the melted chocolate and place on wax paper. let harden and then decorate with those icing tubes or while still wet roll in sprinkles, nuts etc.
I will also be making them for Christmas. Placing two marshmallows on a stick and just adding some colored chocolate for a hat, a couple of eyes and some buttons, using candies and the melted chocolate as glue. Also make some light brown chocolate by mixing white and dark and dip one mallow and then add some broken pretzels for antlers, a red candy for a nose and there you have Rudolph. There are a great many things you can make with these and the kids just go nuts for them. it only took me about an hour to make 120 of them for the party. Easy and delicious.