Mix the butter with the chives, season. Set aside 1/2 tbsp, cover and refrigerate the rest.
Place the potato slices, rosemary, salt and pepper in a bowl and mix thoroughly. Layer in a rosette shape in the prepared dishes, brushing each layer with a little butter.
Bake for approx. 30 mins. in the centre of an oven preheated to 220°C.
Heat 1/2 tbsp of the reserved chive butter, sauté the vegetables for approx. 2 mins., cover and cook for a further 10 mins., season.
Pat the mussels dry. Heat the butter in a non-stick frying pan. Fry the mussels over a medium heat for approx. 2 mins. on each side, season.
Using a knife, separate the potatoes from the sides of the dishes, use a spoon to lift them out of the dishes and plate up with the vegetables. Serve the scallops alongside and top with the chive butter.