Your original sentences contain an error, prior to combining. This sentence contains an instance of disagreement between subject and verb number: one is singular, the other plural:
The cake were delicious
The combined sentence uses the singular "cake", which means that you're treating "cake" as something uncountable. While this is possible and grammatically correct, it has a different nuance. Uncountable "cake" refers to an undifferentiated quantity of cake material, such as many cakes crumbled or mashed together, or simply a viewpoint of not caring about distinction between individual cakes (because there are so many, or because the perspective is one of indiscriminate consumption, or voluminous production, or something like that):
Joe's stomach was so full of cake he could hardly move. That was the most cake he had ever eaten.
Mom sure baked a heck of a lot of cake over the holidays last year.
A change to this nuance is inappropriate; the original sentences that are to be combined refer to a tray containing individual cakes.
The sentences are each a good combination of the originals if "cakes" is pluralized.