While guests meander about her East Austin backyard clad in flowing dresses and gold headpieces, sipping pomegranate cocktails, 24-year-old Bay Stewart is greeting these strangers as if they were her lifelong best friends—while running around putting the final touches on a five-course dinner. Twelve attendees have paid $72 apiece to attend ATX Supper Club’s monthly dinner, which, this September, is a five-course Dionysian feast cheekily inspired by the hedonistic bacchanals of the Greek deity. (Stewart, a classics minor in college, wrote a thesis on the cult of Dionysus and describes Greco-Roman history as “the messiest tea.”) Without removing her embroidered denim apron, she opens the dinner with a speech: “Let’s just acknowledge that we’re kind of nervous to open up to strangers, but this is…