How to prevent Orecchiette from sticking to each other while cooking? How to separate in water?
Adding your pasta to cold water before boiling it may help. You will need to stir more often overall, but the shells won't initially stick together as soon as you add them to the water, and then you can stir to prevent the sticking as they become softer. 

Harold McGee in a New York Times column wrote this:


  I prefer starting with cold water, because the noodles don’t stick together at all as they go into the pot, and because I don’t notice a difference in flavor once they’re drained and sauced.


What happens is that the starch on the noodles gets rinsed off in the water before it can gelatinize and stick to everything. So you will have to stir even before the water gets warm.