01 -
Line an 8x8-inch baking dish with parchment paper leaving a slight overhang; secure edges with binder clips to prevent folding. Lightly spray the parchment with nonstick cooking spray.
02 -
Place semi-sweet and milk chocolate chips, sweetened condensed milk, hot chocolate mix, and butter pats in a medium microwave-safe bowl.
03 -
Microwave at full power for 1 minute, stir well, then continue heating in 45-second increments, stirring after each until smooth and fully melted, approximately 2.5 to 3 minutes.
04 -
Stir in vanilla extract until fully blended. Add 2 cups of miniature marshmallows and mix well.
05 -
Microwave the mixture for 20 to 30 seconds and stir 2 to 3 times to soften the marshmallows.
06 -
Pour the mixture into the prepared dish and spread evenly using an offset spatula.
07 -
Evenly sprinkle the remaining 2 cups of miniature marshmallows on the fudge surface and gently press to adhere.
08 -
Cover the dish with plastic wrap and refrigerate for 2 hours or until firmly set.
09 -
Once set, remove binder clips and lift the fudge from the pan using the parchment paper overhang onto a cutting board.
10 -
In a microwave-safe bowl, heat semi-sweet chocolate chips and vegetable oil for 30 seconds, then stir until smooth.
11 -
Drizzle the melted chocolate over the marshmallow topping. Allow to set before cutting into a 5 by 5 grid using a sharp knife. Store chilled until serving.