Well, for once, the Isekai MC isn't magically preparing 5 stars meals out of nowhere. With knowledge impossible to get or remember for the common (wo)man...
Seems like her meals are fairly simple, and she does a lot of trial and error.
And in my city, when a new restaurent with a strange and exotic menu opens, it gets popular fairly quick too.
Why are Shoujo Isekai manga so much more believable than Shonen ones...