Preheat the oven to 220 C, 200 Fan, Gas 7. Score the skin of the duck breasts several times in a diamond pattern.
Place the duck on a non stick baking tray and season with salt and pepper. Cook in the oven for 15-20 minutes.
While the duck is cooking put the wine, blackcurrant jam and creme de Cassis ( if using) in a saucepan. Bring to the boil then reduce the heat and simmer for 10-15 minutes. The sauce should be reduced and syrupy. Season to taste, remove from the heat and set aside.
Remove the duck from the oven, rest for a few minutes then cut each breast diagonally into slices about 1 cm thick. Discard the skin for a healthier option.
Arrange the duck on warm plates and drizzle over the sauce.