I bake my chicken parm, and I occasionally even use just regular boneless, skinless chicken breasts, and don't bother pounding them out flat. Flat gives you more crust to chicken, but is also a bit more unhealthy since its a lot more breading for the same(or less) amount of meat.
I just take my chicken breasts, coat them lightly in flower(flower+salt+pepper), knock off excess, dip in egg white wash(2 egg whites will do 2 big chicken breasts just fine), then roll in panko bread crumbs(I mix all of my herbs and parmesan cheese in with the breadcrumbs). Put in a glass baking dish that has been sprayed with non-stick spray, and then also spray the top of the breadcrumbed chicken with the spray, so the crumbs turn into a nice golden brown crust, but not burnt/dry(that little bit of extra oil really does help).
Cook for about 10-15 minutes, pull it out of oven, add your marinara/tomato sauce to the pan, and cover each piece of chicken with mozzarella/provalone/parmesan cheese, then back into the oven for another 10-15 minutes. Those cooking times are for full chicken breasts, un-flattened. Takes about 25-30 total minutes at 400 to bake all the way through, but you only want to add the cheese halfway, you don't want it in the over for 30 minutes, it could burn.
Basically, it's this recipe:
Chicken Parmesan Recipe : Ellie Krieger : Food Network