is it possible to create a custom recipe? if so, how?

Yes. All recipes are using Minecraft's new datapack system, which means you can easily modify them or add more.
For information on how to make datapacks for create, check out this wiki entry by Grimmauld: https://github.com/Creators-of-Create/Create/wiki/Change-Recipes

Yes. All recipes are using Minecraft's new datapack system, which means you can easily modify them or add more.
For information on how to make datapacks for create, check out this wiki entry by Grimmauld: https://github.com/Creators-of-Create/Create/wiki/Change-Recipes

There is no Change-Recipes page anymore, it redirects to the general wiki. Is this intended?

EDIT:
You can still add new recipes by utilizing the datapack functionality although the wiki doesn't mention it.

The article was renamed, and therefore the URL changed. It can now be found here: https://github.com/Creators-of-Create/Create/wiki/Custom-Recipes