Expressing the state of something that is planned to be executed

Solution 1:

A short way to say it would be:

Where can I hide the cake I will bake?

Where can I hide the cake once it's baked?
Where can I hide the cake I'm going to bake?

I have a feeling there are quite a number of ways of saying this...

You could use the expression "in the works" to imply that your cake is not ready yet, but it will be ready soon.

in the works. Fig. being prepared; being planned; being done.

An example sentence is:

"My cake is in the works, but I will need a place to hide it. Do you know of any?"

I just made the expression longer, but in the works is an idiomatic way to express "the planned activity of baking".