This blog gets searched for subjects like "bread oven building class" or "pizza oven building class" or even "brick oven building class" (according to my blog's search statistics).
While I have a few posts here about specific classes, I do maintain a more general list of class information on a page as part of my main Quest for Ovens links pages. The class information is organized by state (for the US) or country.
The information might not be current; I record classes as I find them mentioned without tidying up past links. Partly that's because a place that once held a class is more likely to do so in the future.
This provides the best info available at the time.
If you are going to be hosting an oven-building class, I would be happy to mention it here and link to it if a link is available. Just leave a comment on the blog or use the mailto link on the web site.