Here is the item again:
You correctly realized that the period after cake creates a problem. But couldn't accept the slice ... is a lonely verb fragment. When you attach a phrase of this type to the end of a main clause, you need no punctuation.
To fix the problem, you chose to do this:
You have correctly employed Punctuation Rule 8:
Main Clause + Ø + Lonely Verb Phrase.
What an intelligent decision!