In the bowl of an electric mixer, combine the butter, lemon juice, cream cheese, shallots, Essence, sherry, salt, mace, cayenne, and chives and mix with a rubber spatula. Add the shrimp and crawfish and mix to combine. Fold in the chives. Transfer to a large bowl, smoothing the top with the spatula. Chill until just firm, not letting the butter get too hard, about 30 minutes.
Serve with croutons.
Yield: 4 servings