This would make a great family or homeschool project. You would first need to research what elements you want to add to your cookbook. Some suggestions are:
table of contents
this for that information
information on zucchini
information on freezing zucchini, or the finished recipes
how to clean and shred the zucchini
You may also want to add a photograph of finished recipes, or of your children making each recipe. A nice two-page spread would be the recipe and picture on one page, and a journaled story about making or eating the dish on the next page.
You will want to use only your favorite holiday zucchini recipes, so you will have to try them all out first. This can be a lot of fun. You will also want to make sure that you now how to prepare relevant recipes for the freezer.
Here are some zucchini recipe ideas:
zucchini mashed potatoes
zucchini in stir-fry
zucchini cake with cream cheese frosting