Prep chicken. Place each chicken breast flat on a cutting board and carefully slice horizontally to create two thin cutlets (4 pieces total). Pat all chicken pieces thoroughly dry with paper towels.
Make seasoning . In a small bowl, combine smoked paprika, dried thyme, dried oregano, garlic powder, onion powder, salt, and pepper.
Season generously. Coat both sides of each chicken piece with the blackening seasoning, pressing gently to adhere.
Preheat pan. Heat cast iron skillet over medium-high heat until very hot, about 5 minutes.
Add oil. Add avocado oil to the hot pan and swirl to coat the surface.
Cook first side. Carefully place seasoned chicken in the hot skillet (work in batches if needed). Cook for 3-4 minutes until a dark crust forms.
Flip and finish cooking. Turn chicken and cook another 3-4 minutes until cooked through (internal temperature 165°F).
Brief rest. Remove chicken from skillet and let rest for 3 minutes before serving to redistribute juices.