From Longman Dictionary of Contemporary Englishmelt in your mouthmelt in your mouthDFif food melts in your mouth, it is soft and tastes very nice → melt
Examples from the Corpus
melt in your mouth• Butter wouldn't melt in his mouth.• Crisp, without the slightest hint of being greasy, it both crunches and melts in your mouth.• From the look of her, butter wouldn't melt in her mouth!• However, when you meet Sean Young she's disarmingly polite and looks as if butter wouldn't melt in her mouth.• She may look like a fire-breathing dragon, but butter wouldn't melt in her mouth.• The meat is juicy and salty, peppery around the edges, and just soft enough to melt in your mouth.• These eggs melt in your mouth. 