for Case of the Secret Sauce by Aaron Rosenberg and David Harrington
Pete and Penny live above Pizzarelli's, the family pizza parlor, in the small town of Rellaville. They're excited when their parents go out of town, leaving them in charge along with their quirky uncle. But everything goes downhill fast when the family's top-secret pizza sauce recipe is lost! Readers figure out puzzles alongside the main characters and those clues lead them to solve the mystery!
Publisher description retrieved from Google Books.