Place the fish stock and vermouth in a 1 quart (1 liter) saucepan. Bring to a boil and reduce to a glaze -- this will take about 20 minutes. Add the cream. Stir and cook until fairly thick -- about 10 minutes. Over moderately high heat, melt the butter in a skillet. When butter is foamy, add the scallops and cook just until opaque -- about 2 minutes. Remove the scallops to a dish and keep warm. Pour the liquid from the skillet into the saucepan with the cream sauce. Cook until sauce is reduced to its original thickness. Add 2 tablespoons (30 ml) of the chervil, the scallops and salt and pepper to taste. Divide scallop mixture among the cases. Top with remaining chervil and freshly ground pepper.