What do Americans call this?
@Whiskeyomega @storybookcat @mrluo @dennison I too am in the Midwest US. That is not a popover. If you fill it with sausage and vegetables and a gravy as you've described, the closest thing I can think of is called a "pot pie" ... usually filled with chicken or turkey, sometimes beef, but not sausage that I've heard of. (But sausage would be good!)
The important part of a pot pie, however, is that it would also have a pastry top on it as well.