01 -
Line an 8x8-inch baking pan with parchment paper, leaving an overhang to lift out the fudge. Spray parchment lightly with nonstick cooking spray.
02 -
Combine sugar, butter, heavy cream, and corn syrup in a heavy-bottomed saucepan. Cook over medium heat, stirring constantly, until a rolling boil is reached.
03 -
Continue stirring vigorously and boil for 4-5 minutes, until a candy thermometer reads 235-240°F.
04 -
Remove saucepan from heat and stir in chopped white chocolate until completely melted and smooth.
05 -
Mix marshmallow cream and vanilla extract into the fudge mixture until well combined.
06 -
Pour ¾ of the fudge mixture into the prepared baking pan, spreading evenly.
07 -
Add unsweetened cocoa powder to the remaining fudge mixture and whisk until fully incorporated.
08 -
Carefully spoon the cocoa fudge mixture over the white fudge. Use a toothpick or skewer to swirl the layers for a marbled look.
09 -
Allow the fudge to cool at room temperature for 1 hour. Cover with aluminum foil and refrigerate for 1 hour or until firmly set.
10 -
Once set, lift fudge from the pan using the parchment overhang and cut into 5x5 or 6x6 pieces with a sharp knife.
11 -
Add chocolate chips and vegetable oil to a microwave-safe bowl. Heat on high in 30-second intervals, stirring after each, until melted.
12 -
Dip tops of fudge pieces in melted chocolate. Let the chocolate set fully before serving.