A trained chef, Byrn, 44, turned her shortcuts and tips into The Cake Mix Doctor, a recipe collection that scaled the cookbook sales charts after it was published last October. "The book validates the way people have been cooking all along," Byrn says. "I'm just saying, it's okay. Don't be ashamed of it."
Byrn began playing around with packaged mixes after the first of her three kids came along in 1990. She soon found that adding ingredients (like buttermilk and orange juice) can mask a mix's failings. Byrn drafted her banker husband, John Whitaker, 47, to take her cakes to work and get his colleagues' reactions. "Nothing more scientific," he says, "than 'thumbs-up' or 'thumbs-way-up.' " After tasting Byrn's orange chiffon cake, St. Louis pastry chef Tim Brennan seconded the motion. "I usually have an aftertaste from chemicals," he says of processed foods. "But that was special."
As Byrn mixes up a sequel, she has little doubt that it will find a hungry readership. "Cakes are a food we have when we're celebrating," she says. "They're part of people's lives."