Defrost for a few hours in the refrigerator or a cold-water bath. Preheat the oven to 400° F. For crispy skin, start by searing the duck breast skin side down in a pan over high heat for about 5 mins. Place the duck in an ovenproof pan and cook it in the oven for about 5 minutes. Let the meat rest for a few minutes, then slice with a sharp knife.