I think in that situation, I would just act as though I was not aware that she was probably muslim. I would just answer as though she were anybody else, and just say what was in them or that I would give her the recipie after the party or whatever.
As others have said, if someone's dietary restrictions are very strict, it's really on them to ask about what foods might contain certain ingredients. Maybe she doesn't follow those restrictions, or is not in fact muslim, or, I guess any number of things.
So just to answer straighforwardly, to "play dumb", I think would solve the problem of feeling awkward, where she wouldn't necessarily know that you know you are actually probably telling her she just violated one of her own religious beliefs, a really big deal, and so she wouldn't be emberassed, not knowing how to react herself. She could just say "okay, that's interesting!" or whatever, and then do whatever she needs to do, if anything, to "make up" for the mistake, and if that's actually not one of her restrictions, you've saved yourself some awkwardness too.