It's almost certain you will overcook them if you try to cook them in the oven. Boneless, skinless chicken breasts cook so quickly.
I'd recommend using the bottom of a heavy, flat pan to pound them (put them between two pieces of plastic wrap or waxed paper) to an even thickness of about 1/2 inch. This way they will cook evenly. Season them with salt and pepper to your taste, and any herbs you like. Heat a small amount of olive oil in a flat skillet large enough to hold all the pieces you are cooking, and when it is just sizzling, put in the chicken. The meat will release itself from the pan when it's ready to be turned over. When you turn it over, you might want to add a couple tablespoons of white wine or dry white vermouth. Let the chicken cook a few more minutes on the other side.
Pour the liquid that remains in the pan over the chicken for a sauce.