In a mixing bowl, add gochujang, ginger, garlic, soy sauce, sesame oil, and sugar together.
Season both sides of chicken with salt and pepper.
Pour marinade over and allow to marinate for 1 hour to 24 hours.
Bake in preheated oven for 30-40 minutes at 200C or until done.
Sprinkle some toasted sesame seeds, and garnish with chopped spring onions.