This quasi-experimental mixed-method study employed both qualitative and quantitative methods to generate a case study of the effect of a tailored blended learning TOT model on improving EFL teachers' professional development. The model assesses teacher trainers' coaching and mentoring performance, as well as tracks the effect on students' achievement. The model is designed to align with the new educational reform “Curriculum 2.0" entailed in Egypt's Vision 2030. A sample of four senior in-service teachers from the foundation and primary stages came from a private Egyptian national language school located in Cairo, Egypt. Each teacher was assigned the same 10-Modules over a 10-week period using the flipped classroom strategy. Kirkpatrick's model of training evaluation was used in this study where the effect of the program was measured on four levels, namely: 1) Reaction, 2) Learning, 3) Attitude, and 4) Results. An additional fifth level was added to the evaluation model to measure the long-term impact of the training. Tools included a pre-post-administered Concept-check Questionnaire, a delayed Concept-check Questionnaire, students' mid-year EFL exam, semi-structured interviews, mentoring/coaching competency checklist, a videotaped reflection, and satisfaction questionnaires. Analysis of triangulated data showed that there was a significant improvement in 1) participants' coaching and mentoring knowledge and skills, 2) attitudes and perceptions of mentors/coaches and 3) students' academic achievement in EFL classes, 4) satisfaction of all stakeholders (i.e., mentors, mentees, parents and students).