Maybe this thread was a year ago, but I would like to help you then. The correct one you can use is, “Ice cream is a kind of dessert”, because ice cream is a singular noun so you may use also a singular adjective.
Nouns used as an adjective has one form. There are also some nouns where we add -d or -ed at the end of the word to make it an adjective. But when used as a real noun in a sentence the form changes to singular or plural.
I hope this helps.
Just for information: some examples of noun adjectives with -d or -ed at the end of the word.