The Center for Professional Advancement is one company that puts on these courses. I believe they are still in business though I haven't received anything from them in a while.
The ASME's International Gas Turbine Institute makes available a home study course entitled The Design of Gas Turbine Engines -- Thermodynamics & Aerodynamics($365 in North America). This is a detailed course (with a grading service) intended for graduate engineers with a knowledge of thermodynamics.