marshmallow

mastery
UK /mɑːʃˈmæləʊ/ US /ˈmɑɹʃˌmɛl.oʊ/nounverb

card 1 of 1 · preposition

It was an apple marshmallow sundae, I recollect. I dug my spoon into it _____ an assumption of gaiety which I was far from feeling.