Eater has a new cookbook. Eaterland, Recipes and Stories from Across the United States, debuting April 28. To celebrate launch week, we’re sharing a sneak peek from the book that focuses on the Wisconsin Supper Club tradition, written by the author of the book’s Midwestern chapter, Amy Cavanaugh. Learn more about the project here . To Really Understand Wisconsin, Eat at a Supper Club Walk into any supper club on a Friday night in Wisconsin, and you’ll find diners sipping brandy old-fashioneds while snacking on relish trays, then tucking into fish fries before finishing the night with minty grasshoppers. The same scene plays out on Saturdays, except with rosy slabs of prime rib taking the place of walleye. It’s an identical tableau all over the state, whether you’re at Benedetti’s Supper Club in Beloit, the Buckhorn Supper Club in Milton, or Ishnala Supper Club in Lake Delton. Supper clubs have been integral to Wisconsin life since the 1930s.…