There was a manga I read fairly recently, and all I can remember is the protagonist specifically mentions to the love interest that "he's made mugwort mochi before with his grandma" and the love interest being confused about mugwort.

Sorry I can't give much more detail, but this phrase is very specific, so I'm pretty sure it's the only manga that's mentioned it and you'd know it if you saw it.

Any help is appreciated!🙏