I'll start by saying that if a woman is shopping late at night by herself, odds are she is single, or is getting stuff for a party. In either case, they are gamable.
"Do you know how to make *food dish* from scratch?"
It's an organic question (in more ways than one). Just be playful with however she responds. Body language is also key. Never tip off that you're hitting on her, and never show interest until she shows IOI/SOI.
If she says yes, then neg her cooking with "

I think that's how they make it in prison. What would be appropriate somebodies' "going away" party?".
If she says no, ask her for a suggestion for something you can make for you're friend's "going away" party. Neg the hell out of that as well. "Hmm... sounds like something they'd serve in prison.

"
Also, if she's nosey, she'll probably ask about the going away party, so have an answer.
That's just an opener. Once you're in like flint, it's a different game.