It all depends on how much you care to fuss over the process. You don't have to wash & dry them, only if you're storing up a lot on your counter for a long period of time. Chickens don't have a sense of smell, and they shouldn't make the connection between crushed shells & their own e g g s. You don't have to bake or microwave them either, but I find it makes it so much easier to crumble them. Whenever I make a dish that uses a lot of e g g s, like quiche or french toast, I save all the shells to return to the chickens. I bake them in a pie pan and crush them with a flat-bottomed coffee mug.