Combine Diamond Crystal(R) Kosher Salt, brown sugar, white sugar, cocoa powder, and chipotle chili powder in a medium sized bowl; stir well. Transfer to a sealable airtight container; set aside until needed. Spice blend will hold for 6 to 9 months at room temperature.
Preheat oven to 350 degrees F (175 degrees C).
Rinse chicken and lightly dry off with paper towel. Place chicken in a heat-proof baking dish.
Liberally rub approximately 1/2 cup seasoning onto chicken; apply at least 30 to 60 minutes prior to cooking. If not cooking within the hour, cover and refrigerate. (If removed directly from fridge, allow to sit at room temperature for 15 minutes.)
Drizzle and gently rub chicken with oil.
Roast in the pan to an internal temp 160 degrees F, approximately 1 hour 15 minutes.
Allow to rest for 20 to 25 minutes before carving or serving.