Preheat the oven to 400 degrees F (200 degrees C).

Mix duck fat, scallions, ginger, and salt together in a bowl.

Place chicken in a baking dish. Add 1 tablespoon ginger pesto under the skin of each chicken breast; massage to spread evenly. Coat chicken with remaining pesto and season with additional salt.

Roast in the preheated oven until chicken breasts are no longer pink in the center and juices run clear, 30 to 35 minutes. An instant-read thermometer inserted into the center of a breast should read at least 165 degrees F (74 degrees C). Let rest for 5 to 10 minutes.