Computational Thinking (CT) has been described as the use of abstraction, automation and analysis skills for problem solving, thus becoming a set of fundamental skills for the 21st century. Many initiatives have emerged to promote early development of CT skills. However, to date, there are no studies in which CT is developed in minority groups, such as individuals with Autism Spectrum Disorders. In this paper we present the design and evaluation of a Game Design Workshop aimed at teenagers with Autism Spectrum Disorders. An analysis of the artifacts produced by the participants of a pilot offering of the workshop was performed using a rubric for CT skills acquisition. The results showed that the participants, all of them with high-functioning autism and no previous experience with programming, acquired intermediate level skills related to CT.