01 -
In a medium saucepan over low heat, combine semi-sweet chocolate chips, sweetened condensed milk, and melted butter. Stir constantly until the mixture is smooth and fully combined.
02 -
Remove the saucepan from heat and stir in vanilla extract and salt until evenly mixed.
03 -
Line an 8×8-inch baking dish with parchment paper, ensuring excess paper overhangs for easy removal.
04 -
Pour the chocolate mixture into the prepared baking dish and spread evenly using a spatula.
05 -
Drop spoonfuls of marshmallow fluff evenly over the chocolate layer. Using a knife, gently swirl the marshmallow into the fudge to create visible ribbons without overmixing.
06 -
Place the baking dish in the refrigerator and chill for at least 2 hours until the fudge is firm.
07 -
Lift the set fudge from the dish using the parchment paper edges, cut into squares, and serve.