Directions

1. 1

   Line an 8x8-inch baking pan with aluminum foil, allowing edges to hang over for easy removal. Set aside. In a medium saucepan, combine the sugar, evaporated milk, and butter. Place over medium-high heat and stir constantly until the mixture comes to a rolling boil, about 10 minutes. Once boiling, reduce heat to medium and continue stirring constantly for 6 more minutes.

2. 2

   Remove the saucepan from the heat and let cool for 1 minute.

3. 3

   Add the semisweet chocolate pieces, dark chocolate, marshmallows, walnuts, and vanilla extract. Stir vigorously until all chocolate has melted, the marshmallows have softened, and the mixture is well combined. Beat by hand for 1 minute to ensure thorough mixing.

4. 4

   Pour the fudge into the prepared pan and spread evenly with a spatula. While still warm, score the surface into 64 squares using a sharp knife (mark an 8x8 grid). Cover with plastic wrap or foil and refrigerate for 2 to 3 hours until completely firm.

5. 5

   Once firm, melt the white chocolate and dark chocolate separately using a double boiler or microwave in 20-second intervals, stirring between each interval until smooth. Pour the dark chocolate evenly across the top of the chilled fudge. Immediately drizzle the melted white chocolate in random patterns over the dark chocolate. Using a small spatula or knife, gently drag and swirl the white chocolate through the dark chocolate to create a marbled effect. Do not over-swirl, as this will blend the colors and lose the pattern.

6. 6

   Return the fudge to the refrigerator for 15 minutes to set the chocolate topping. Using the foil edges, lift the entire fudge block from the pan and transfer to a cutting board. Cut along the pre-scored lines to separate into squares.

7. 7

   Store the fudge in an airtight container in the refrigerator for up to 1 month. Makes about 2 pounds or 64 pieces.