1 tablespoon butter
2 large shallots (finely minced)
2 tablespoons dry white wine or sherry
1/2 cup (4 ounces) cream cheese (softened)
1/4 cup mayonnaise
2 tablespoons heavy (whipping) cream
1 1/2 tablespoons Dijon mustard
  Kosher salt (to taste)
  cayenne pepper (to taste)
1 tablespoon finely minced fresh tarragon
1 pound lump crabmeat (drained well)
1/2 cup Ritz cracker crumbs
1/2 cup finely grated parmesan cheese