Rich and creamy, this hot crab dip is an elegant addition to any celebration. It can be made up to 2 days in advance; store, covered, in the refrigerator. Before cooking, allow the crab mixture to return to room temperature. Serve with toasted croutes made from a French baguette, or spread on your favorite crackers. There won't be any leftovers when you serve this tasty hors d'oeuvre at your next party!
Melt the butter over medium-high heat in a medium-size skillet. Add the shallot and cook, stirring frequently, until it softens, 3 to 5 minutes. Add the wine and cook until the liquid evaporates, about 2 minutes. Remove the pan from the heat.
Add the cream cheese, mayonnaise, cream, and mustard to the skillet, stirring with a wooden spoon or rubber spatula to blend. Transfer the mixture to a large bowl.
Stir in the salt, cayenne, and tarragon. Add the crabmeat, stirring gently to combine. Transfer the mixture to a shallow baking dish.
Combine the cracker crumbs and parmesan in a small bowl. Sprinkle the mixture over the top of the crab dip.
Position a rack about 8 inches from the broiler. Preheat the broiler on high.
Broil the crab dip until it's hot and the topping is golden, 5 to 8 minutes. Serve warm with crackers or croutes.