Use a fork to score the duck breasts through the skin and fat but don't cut into the meat.
Heat a large, heavy frypan on medium high heat and fry the duck breasts, skin side down, until the skin browns and fat runs out; about 10 minutes.
Remove the breasts from the frypan and pour off most of the fat. Return breasts to frypan and fry skin side up for another 10 minutes.
Remove breasts from frypan and allow to rest on a baking tray. Pour most of the fat out of the frying pan leaving only a coating.
Mix the salt, cinnamon and sugar together and sprinkle over the skin of the duck breasts.
Mix together the red wine, cassis and cornflour in a small bowl. Pour into the pan and simmer for 3 minutes, stirring constantly, until the sauce is thickened. Add the raspberries and simmer for another minute until heated through.
Thinly slice the duck breasts, pour a little sauce over the top and serve warm.