Sprinkle the chicken pieces all over with salt and pepper.
Heat half the butter and all the oil in a heavy frypan and cook the chicken pieces until golden brown all over. Pour off most of the fat and add prosciutto, sage and wine. Cover and cook until tender, about 20 minutes.
Remove the chicken and put on a hot serving plate. Melt the remaining butter in the pan to make a sauce. Serve the sauce separately.