Yes, you can say “I like apple” if you are talking about the fruit pulp, its texture or its taste; i.e. when it is uncountable.  The same is true for any fruit, 

>- *The median proportions of food types selected are shown in Figure 1 where it can be seen that both species [rats] tended to **prefer banana and avocado** to the other foods offered.* [(source)][1]
>
>- Infants can be fed **puréed apple** after five months of age.

And when we talk about dishes, in this case dessert, the singular is used. 

>- ‘Twin Peaks’ the groundbreaking drama from David Lynch starring Kyle MacLachlan as FBI Special Agent Dale Cooper, the detective with a **predilection for cherry pie**, and a nose for mystery,... [(source)][2]


But normally when we use the word *apple*, we think of it as something that is countable, that we can pick up and bite into. We are talking about apples in *general*, not about a *single* apple. Which is why the phrase ***I like apples*** will always be far more common than *I like apple.*


  [1]: https://books.google.it/books?id=8wXxAAAAMAAJ&q=%22prefer%20banana%22&dq=%22prefer%20banana%22&hl=en&sa=X&ved=0ahUKEwjqipu8tpzRAhWKcVAKHaaRCus4ChDoAQg-MAg
  [2]: https://nz.lifestyle.yahoo.com/entertainment/tv/a/17260891/tv-radar-new-shows-this-may/#page1