Turn ice cream cones upside down, and decorate with green frosting.
Use your favorite icing recipe, or for a super quick version add green food coloring to a can of pre-made vanilla frosting. No green food coloring? That is fine. Leave it white for a snowy version of trees.
If you have a star tip for a pastry bag that would work great. If not put the frosting into a baggie and cut the tip off the corner of the bag. Pipe icing onto the cone in overlapping lines similar to the look of branches.
Next decorate the trees with your favorite candies. Mini M&Ms would work great for ornaments, or lined up as garland. There is no end to what you can do with a variety of candies.
This way your kids get to do a fun project, and eat their favorite part with no cake to throw away!
These trees would also make a great addition to any gingerbread creation.