Among the new educational tools and new ways of teaching/learning of the last 20 years, educational approaches based on constructivism are of great interest because they offer the possibility for students to build scientific concepts from experimental observations. Cooking is truly a universal topic--it can be considered a true multidisciplinary science as it incorporates chemistry; biology; and to a lesser extent, physics. Therefore, it offers the possibility to perform many experiments and to evaluate them with all five senses, which is perfect for educational purposes, and in particular for children. The authors introduce a fun approach, mixing science and cooking, that involves several kinds of students and teachers: engineering students (ages 20-22), cooking students (ages 18-25), secondary school students (ages 14-15), and their respective teachers. This article reports on using chocolate as the theme. After a presentation of the project and the lesson, the benefits and difficulties of this approach for the different participants are discussed. A specific focus is given to the engineering students, who were simultaneously teachers and learners.