The word chocolate can be used as a countable noun. The word "chocolate" itself is an uncountable noun. Chocolate refers to a kind of food, which cannot be completely counted. For example, "I have three bars of chocolate" is not the correct expression. But quantifiers can be used to describe quantities, such as a box of chocolates, a bar of chocolates and so on. Therefore, the word "chocolate" can sometimes be used as a countable noun in different contexts.