The question wasn't about first team squad, it was about the academy producing players.
Off the top of my head, Chalobah, Mount, Tomori, Zouma, Ake are all playing regular PL or Championship football and have all come through the academy. I'm sure there are many more
You probably can if you throw stupid amounts of money around. Chelsea seem to be doing OK with theirs - but don't they do it by signing up just about every youngster going?