Score the duck breasts with a criss-cross pattern or parallel cuts through the skin, being careful not to cut all the way to the flesh. Season well, then set aside to bring the meat to room temperature.
Put the breasts skin-side down in a cold frying pan and slowly heat the pan. This will melt the fat and help the skin to crisp up without burning.
Fry the breasts, letting the fat melt out and the skin crisp up. Keep frying until the skin is crisp and brown and you've melted out as much of the visible white fat as possible. This can take up to 10-15 mins.
Pour the excess fat into a ceramic or glass dish (reserve it for roasting potatoes).
At this stage, you have a couple of options for cooking the meat: turn the breasts, add the butter and swirl the pan, then cook for 5 mins until the meat is browned all over (the meat should feel soft but spring back slightly when pressed); alternatively, heat the oven to 180C/160 fan/gas 4 and cook for 5-6 mins for a rosy pink flesh or 10-12 mins if you'd like it well cooked. If you have a meat thermometer, it should read 54C for rare, 61C for medium and 65C for medium/well done.
Rest the duck breast for 10 mins before slicing to serve.

Cook Before Eating. Consume On Day Opened. Store Below 3°C or Freeze on day of purchase for 6-9 Months. Defrost thoroughly in Fridge before cooking.

Chippenham Unit
The Black Farmer, Unit 10, Bumpers Farm Enterprise, Vincients Road, Chippenham, SN14 6QA

Brixton Store
The Black Farmer Brixton Farmshop. 25-27 Market Row, London SW9 8LD

White City Store
The Black Farmer, Unit 1, 2 Television Centre, 101 Wood Lane, White City, W12 7FR