How do you make a Rex Jelly cake?

It seems you're asking about a "Rex Jelly Cake." Unfortunately, this isn't a common or known recipe. It's possible there are a few reasons why:

* It's a regional or family recipe: This cake might be a unique recipe passed down through generations or popular in a specific area.

* It's a misspelling: Maybe you're thinking of a similar dessert with a different name. Double-check the spelling or any other details you might have.

* It's a fictional creation: It's possible this cake is from a book, movie, or TV show!

To help me find the right recipe, can you provide more information?

* Do you have a picture of the cake?

* What kind of flavors or ingredients do you think it might have?

* Where did you hear about this cake?

Once I have more information, I can do my best to find the recipe for you or point you in the right direction.