01 -
Line an 8 x 8-inch baking pan with aluminum foil and lightly grease with butter or nonstick cooking spray.
02 -
In a microwave-safe bowl, mix half the sweetened condensed milk (7 oz), chocolate chips, and 1 tablespoon butter. In a separate microwave-safe bowl, combine the remaining sweetened condensed milk (7 oz), peanut butter chips, and remaining 1 tablespoon butter.
03 -
Microwave both bowls on high in 30-second intervals, stirring after each interval, until the chips are fully melted and the mixtures are smooth.
04 -
Stir 1 teaspoon vanilla extract and 4 ounces cream cheese into each bowl. Microwave both mixtures again for 30 seconds on high, then stir until smooth and fully combined.
05 -
Pour two-thirds of the chocolate mixture into the prepared pan. Spoon half the peanut butter mixture over the chocolate layer. Add the remaining chocolate mixture, then top with the remaining peanut butter mixture.
06 -
Drag a knife through the layers to create a marbled swirl effect. Refrigerate the pan for 3 hours or until the fudge is firm. Store in a sealed container in the refrigerator.