Preheat the oven to 425°F (220°C). Line a 9x13-inch baking pan with aluminum foil.
In a small bowl, combine the brown sugar and Creole/Cajun seasoning until evenly mixed.
Pat the chicken breasts dry with paper towels. Coat both sides of each breast with the brown sugar mixture, pressing gently so the mixture adheres. Reserve any leftover mixture.
Place the coated chicken breasts in the prepared pan and sprinkle any remaining brown sugar mixture over the top.
Bake in the preheated oven for 20 to 25 minutes, until the chicken reaches an internal temperature of 165°F (74°C).
Turn the oven broiler to high and broil the chicken 1 to 2 minutes, watching closely, until the brown sugar caramelizes and the surface is browned but not burned.
Remove from the oven and let the chicken rest a few minutes before serving.