na-adjective, noun which may take the genitive case particle 'no'
burnt to a crisp; charred
Emphatic, colloquial expression for something severely burnt or scorched. Often used in casual speech.
トーストが焦げ焦げになっちゃった。
The toast got burnt to a crisp.
焦げ焦げの肉はちょっと苦い。
Charred meat is a bit bitter.