Nancy, George, and Bess are taking a cooking class at Le Gourmet. And they are learning to make desserts! Nancy can't think of a sweeter way to spend her spring break than whipping up tasty concoctions with her two best friends. Then at the end of the week, Monsieur Jadot will name one student "Top Chef" at a special ceremony. Nancy can't help but wonder, will her dessert take the cake?

But this sugary sweet class turns sour when whacky things start happening, and Nancy discovers that someone is tinkering with the recipes! Smells like a mystery—and one Nancy must solve before dessert is served!