Recent research suggests that training teachers as learning designers helps promote technology-enhanced educational innovations. However, little attention has been paid so far to the interplay between the effectiveness of Teacher Professional Development (TPD) instructional models promoting the role of “teachers as designers” and the capabilities (and pitfalls) of the heterogeneous landscape of available Learning Design (LD) tooling employed to support such TPD. This paper describes a mixed method study that explores the use of a novel Integrated Learning Design Environment (ILDE) for supporting a TPD program on Information and Communication Technologies (ICT) and Collaborative Learning (CL). 36 Adult Education (AE) and Higher Education (HE) in-service teachers, with little experience on both CL and ICT integration, participated in a study encompassing training workshops and follow-up full-lifecycle learning design processes (from initial conceptualization to implementation with a total of 176 students). The findings from our interpretive study showcase the benefits (and required effort) derived from the use of an integrated platform that guides teachers along the main phases of the learning design process, and that automates certain technological setup tasks needed for the classroom enactment. The study also highlights the need for adaptation of the TPD instructional model to the learning curve associated to the LD tooling, and explores its impact on the attitude of teachers towards future adoption of LD practices.