How to Make It
Line a 13- x 9-inch baking dish with aluminum foil, allowing 1 to 2 inches to hang over side of dish.
Combine brown sugar, granulated sugar, molasses, butter, evaporated milk, ginger, cinnamon, salt, allspice, cardamom, cloves, and nutmeg in a medium, heavy-bottom saucepan over medium. Bring to a boil, stirring constantly, until a candy thermometer reaches soft-ball stage (between 234°F and 237°F), about 11 to 12 minutes.
Add white chocolate, marshmallow creme, and vanilla; cook, stirring rapidly completely melted and all ingredients are evenly incorporated. Remove from heat, and immediately pour mixture into prepared dish. Sprinkle with gingersnap crumbs and crystallized ginger.
Cool completely on a wire rack, about 2 hours. Cover tightly with aluminum foil, and store in refrigerator. To serve, cut fudge into 1-inch pieces.