It's more of an education degree, the field draws from pedagogy, behavioral psychology, and educational technology.
There is an aspect of it that relies on 'design' in terms of how a course is structured and how the course parts are both organized and how the path through it is structured for the students.
In full disclosure, this is what my masters degree is in so I went the long way. And I am not accustomed to pointing others to a '1 and done' course.
I took a cursory look around, Coursera seems to have a decent offering. https://www.coursera.org/learn/teach-online