Take a 9-inch square baking pan and line it with parchment paper, ensuring that it covers the bottom and sides. This will make it easier to remove the fudge once it's set. Set the pan aside for later use.

Before starting, gather all the ingredients needed for the fudge. Measure them out accurately according to the recipe to ensure the perfect balance of flavors and textures.

In a saucepan, combine the butter, evaporated milk, brown sugar, and granulated sugar over medium heat. Stir continuously until the mixture comes to a gentle boil.

Once the mixture is boiling, continue stirring constantly to prevent it from burning. Let it boil for about 10 minutes to thicken slightly and develop a rich flavor profile.

After 10 minutes, remove the saucepan from the heat source. Stir in the marshmallow creme and vanilla extract until everything is well combined and smooth.

Divide the fudge mixture evenly into two separate bowls, as you'll be creating two different layers for the fudge.

To one bowl of the fudge mixture, add the butterscotch chips and half of the chopped walnuts. Stir until the butterscotch chips are completely melted and the mixture is smooth and uniform.

In the other bowl of the fudge mixture, add the semi-sweet chocolate chips and the remaining chopped walnuts. Stir well until the chocolate chips are fully melted and the mixture is smooth and well combined.

Pour the butterscotch fudge mixture into the prepared baking pan, spreading it out evenly with a spatula. Then, carefully pour the chocolate fudge mixture on top, spreading it evenly to create two distinct layers.

Place the pan of layered fudge into the refrigerator to chill and set for at least 4 hours, or until firm to the touch.

Once the fudge is thoroughly chilled and set, remove it from the refrigerator. Use a sharp knife to cut the fudge into squares of your desired size.

Serve the delicious two-tone fudge squares on a platter or store them in an airtight container in the refrigerator until ready to enjoy. Be sure to share with family and friends and savor every bite of this delightful homemade treat!