From Wiktionary, the free dictionary
Onomatopoeic.
knaske (imperative knask, present tense knasker, passive knaskes, simple past knasket, past participle knasket, present participle knaskende)
- audibly chew, munch
Slutt å knaske på eplet ditt!- Stop munching your apple!
- “knaske” in The Bokmål Dictionary.
- “knaske” in Det Norske Akademis ordbok (NAOB).