Position an oven rack 4 inches below the broiler element and heat the broiler. Butter a medium gratin dish.
Combine the cream cheese, mayonnaise, mustard and cayenne pepper in a bowl. Season with salt and pepper. Add the tarragon and wine and stir until smooth. Using a large spatula, fold in the crabmeat, taking care not to break the lumps. Taste and adjust the seasoning with salt and pepper.
Transfer to the prepared dish and top with the breadcrumbs. Broil until golden brown, about 5 minutes, depending on the strength of your broiler.
Serve warm on crackers topped with both chopped and sliced jalapenos and hot sauce on the side.