Baking course online
It might be easier to find handbooks or informational sites than classes specifically, as the former can be put up once and left there, whereas the latter requires a teacher be present for each iteration of the course.

I found a good bread-making handbook at The Fresh Loaf; they also have lessons on specific topics. Prepared Pantry has a free baking cookbook as well, plus lessons, though their classes are done I believe at their store location.