Advanced Author / Category Template?

I made a list of categories by author (with counter), and it works perfectly fine! Now I need my readers to be able to proceed to see a list of the blogposts in that Category by that Author. I know how to do that manually, but I have 8 authors and around 50 categories!

Basically what I need is a template that filters by category and author, but it has to happen automatically ~ like it’s some kind of magic or something 😉

Anyone that knows where to begin? I don’t really even know what to ask for here, so if you have a link or a tutorial or something, it would be of great help!

Thanks!