Slice chicken breasts horizontally to create cutlets.
Pound cutlets to 1/3-inch thickness.
Mix spices in a shallow dish.
Coat cutlets with the spice mixture, shake off excess, and place on a baking sheet.
Heat 1 tbsp olive oil in a 12-inch cast-iron skillet over high heat until smoking.
Add 1 tbsp butter, swirl to coat.
Sear six cutlets for 2 mins, pressing with a spatula.
Flip and press again, cook for 1 min.
Transfer to a wire rack over a baking sheet.
Wipe skillet, add remaining butter, and repeat the searing process with remaining cutlets.
Rest cutlets on the rack for 3 mins before serving. Store leftovers in the fridge for up to 3 days.