What if the metatheory is itself intuitionistic?

Question

Usually, even in intuitionistic logic, the metatheory is classical. That is, to give just one example, either something is a theorem of intuitionistic logic, or it is not. That is an example of a metatheoretic instance of the law of excluded middle. But, my main question is, has anyone introduced a truly intuitionistic logic, where even the metatheory is intuitionistic? I would like to see such a paper or a book that does that.