Position rack in middle position and preheat oven to 425°F (218°C).
Line rimmed baking sheet with parchment paper or aluminum foil for easy cleanup.
If using regular chicken breasts, place between plastic wrap and pound to ½-inch thickness using a meat mallet. For pre-sliced thin breasts, verify uniform thickness.
Remove chicken from refrigerator 20 minutes before cooking to reduce thermal shock.
Using paper towels, thoroughly dry chicken surfaces to promote browning.
In a small bowl, combine salt, pepper, garlic powder, paprika, oregano, and cayenne (if using). Brush chicken with oil on both sides, then apply seasoning mixture evenly.
Place seasoned breasts on prepared baking sheet, ensuring at least 1 inch between pieces for proper heat circulation.
Place in preheated oven and bake until internal temperature reaches 163°F (73°C), approximately 12-15 minutes.
Remove from oven and loosely tent with foil. Rest for 5 minutes to allow for carryover cooking and redistribution of juices.
Confirm internal temperature has reached 165°F (74°C) before serving.