Peel and dice the sweet potatoes. Heat the oil in a wide pan and sweat the potatoes briefly. Then add enough water to cover the bottom of the pan and the stock granules, put a lid on the pan and cook over a low heat for 10-15 minutes.
At the same time season the chicken breasts lightly with salt and pepper and wrap each in two slices of bacon. Heat the clarified butter and brown the bacon-wrapped chicken breasts on all sides with the rosemary. Then wrap each breast in aluminium foil with a sprig of rosemary and cook in a preheated oven (180°C) for 12-15 minutes, until done.
Peel and halve the shallots. Add the butter to the fat left from frying the chicken and fry the shallots. Dust with icing sugar and cook until lightly caramelised. Deglaze with cognac and stock, season with salt and pepper and simmer until reduced slightly. Take the meat out of the oven and add the cooking juices to the shallots.
Mash the sweet potatoes and arrange attractively on warmed plates with the meat and shallots. Serve hot.