Preheat the broiler and position a rack 8 to 9 inches below the heat.
If the Vacherin box is stapled together, simply place it on a sheet pan. If the box is glued together, wrap a piece of aluminum foil tightly around the bottom and sides (not the top) before placing it on a sheet pan. (Yes, you will be broiling the cheese in the box.) With a small sharp knife, remove and discard the top rind of the cheese. Pour the white wine over the cheese.
Broil the cheese for 2 to 3 minutes, watching carefully so the box doesn't catch on fire. Remove from the oven, sprinkle generously with fleur de sel and pepper, and serve immediately with toasted breads and cornichons. I put a small spoon in the cheese for people to help themselves.