In a saucepan, cook the sweet potatoes (whole) in boiling water until tender. Drain, peel and finely mash with the sour cream. Season with salt and pepper.
Preheat the oven’s broiler.
In a saucepan, melt the butter. Add the flour and cook for 1 minute, stirring over medium heat. Whisk in the milk. Add the fennel seeds, white wine and chives. Stir until it thickens. Season with salt and pepper.
With a pastry bag with a fluted tip, pipe the purée around the shells. Place four scallops in each shell.
Drizzle on the sauce. Sprinkle with breadcrumbs and cheese. Bake in the middle of the oven for 5 to 8 minutes. If necessary, place the shells immediately below the heating element to brown slightly.
The shells can be prepared in advance and refrigerated. You will cook them at the last moment.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.