Instructions

• Line an 8-inch or 9-inch square pan with foil and lightly spray the foil with cooking spray; set the pan aside.
• In a microwave-safe bowl, combine 1 1/2 cups semi-sweet chocolate chips, half of the 14 oz sweetened condensed milk, and 1 tablespoon of the butter.
• In a second microwave-safe bowl, combine 1 1/2 cups Reese's peanut butter baking chips, the remaining half of the sweetened condensed milk, and the remaining 1 tablespoon of butter.
• Microwave one bowl at a time on high for 30 seconds, stir, then continue microwaving in short intervals (stirring between each) until the mixture is fully melted and smooth and glossy. Repeat for the second bowl.
• Stir 1 teaspoon of the vanilla extract into each melted mixture (1 tsp into the chocolate mixture and 1 tsp into the peanut butter mixture).
• Spoon the chocolate and peanut butter mixtures into the prepared pan, alternating spoonfuls and spreading lightly so the two flavors form layers and ribbons rather than one solid block of a single flavor.
• Evenly sprinkle half of the miniature marshmallows and all of the roughly chopped nuts over the top of the layered mixtures.
• Use a spatula or the tip of a knife to cut through the layers several times to create a swirl and to help distribute the marshmallows and nuts through the top layer.
• Scatter the remaining miniature marshmallows on top and press them down gently so they stick into the fudge surface.
• Let the pan cool to room temperature, then transfer to the refrigerator to chill until the fudge is firm.
• Remove the chilled fudge from the pan using the foil, peel off the foil, and cut into squares.
• Store the cut squares in an airtight container.