Pat the chicken breasts dry with paper towels to ensure a good sear. Coat both sides evenly with olive oil, then apply the blackened seasoning generously to all surfaces, pressing it slightly so it adheres. Let the seasoned chicken sit at room temperature for 5 minutes while you preheat your oven to 375°F—this allows the seasoning to set and helps the chicken cook more evenly.

Melt the butter in a large oven-safe skillet over high heat until it foams and just begins to turn golden. Carefully place the seasoned chicken in the pan and sear for 5 minutes on the first side without moving it, then flip and sear the other side for another 5 minutes until a dark crust forms. Transfer the entire skillet to the preheated 375°F oven and bake for 35-45 minutes until the chicken reaches an internal temperature of 160°F when measured with a meat thermometer at the thickest part.

Remove the chicken from the oven and let it rest in the pan for 5 minutes—this allows the juices to redistribute, keeping the meat moist and tender. I like to squeeze fresh lime juice over the chicken right after resting, as it cuts through the richness of the butter and adds brightness that complements the blackened crust. Transfer the chicken to serving plates, top generously with mango salsa, garnish with fresh cilantro, and serve immediately.