Preheat oven to 350°. Line a baking sheet with aluminum foil. Spray it lightly with cooking spray. Unpack, then pat chicken breasts dry with a paper towel and place them on your baking sheet.
If your chicken breasts are super "uneven" and much thicker on one side, put the chicken between two pieces of plastic wrap and gently pound out the thicker side until it is more-less the same thickness as the rest of the chicken breast.