This plugin adds craftable fireballs. They seem like a perfectly original item. This also disables fire charge crafting, but you can always delete those lines of code with a text editor.
The plugin starts automatically when you load the script, so it is lightweight and hands free.
This plugin requires Skript. You can download it from the bukkit page.
Place the .sk file in the /plugins/skript/scripts folder
You also need SkQuery to run the resource, download it from the link below.
The shapeless recipe is ghast tear, coal block, blaze rod, and gunpowder.
You can also edit the recipe to your liking, just make sure there are 9 items including air total.