Didn't we answer this yesterday? Both are correct. If you use the uncountable form, 'Do you want any cake?', this means 'a certain amount of the cake which is available'. You'd say this, for example, if you have a large cake and you are offering someone a piece of it. If you use the countable plural form, 'Do you want any cakes?', you are suggesting that the other person take several cakes. For example, if you have a lot of small cupcakes and you want to get rid of them, you might say this. Note that you could also use the uncountable form here.

Thanks so much!! If you reply it in answers, I can choose you as the best one, Brend!!

For the interrogative statement, I would ask, "Do you want any cake?" Cake, this context, has been used to contract, "Do you want (a slice of) cake?" In formality, I guess you can say, "Do you want any cakes", but this should be used if you're selling multiple cakes, as if you were the owner of a bakery. Cheers!