It doesn't matter how many stars you earn on each Episode, as long as you get at least 1. Keep in mind that you also have to complete all bonus levels as well. You don't have to finish the Golden Egg levels for this achievement, but you will of course for Egg Master.
As I said in the notes above, don't go into this thinking that an Episode is essentially beating Level 1-1 - 1-21. You will notice that in the entire episode you are working on that there are 2 or 3 levels to beat in order to finish 1 Episode. Keep this in mind as some of you may wonder why you didn't unlock a certain achievement yet.