Is crumbled a noun

The Word 'crumbled' is the past tense, past participle of the verb to crumble. The past participle of the verb also functions as an adjective. Examples:

Verb: I crumbled some cookies over the top of the icing.

Adjective: A crumbled ruin was all that remained of my barn after the tornado.

The Word crumble is a noun as a Word for a type of dessert. Example:

Noun: The lemon crumble will be ready in time for dinner.