Before starting, line your 9 inch cake pan with foil or parchment paper.
Place chocolate and butterscotch chips into a medium sized pot with the sweetened condensed milk on the stovetop.
1 bag (12 ounces) semisweet chocolate chips, 1 cup butterscotch chips, 1 can (14 ounces) sweetened condensed milk
On low to medium heat, melt the chocolate and butterscotch chips and combine with the sweetened condensed milk until it is smooth. Stir often.
Save the empty condensed milk can and cover in foil or a plastic sandwich bag. Place the can in the center of the covered cake pan.
Stir in the vanilla and remove the pot from the heat.
1 teaspoon vanilla extract
Add in the nuts and marshmallows and stir until mixed in well. If you want whole marshmallows in your fudge, only add half of the marshmallows - stir until smooth, then gently fold in the remaining marshmallows, stirring just until they are added to the chocolate, then pour the fudge into the pan.
8 ounces walnuts, 2 cups mini marshmallows
Pour the fudge mixture into your prepared cake pan around the covered sweetened condensed milk can, keeping the can in the center.
If adding gumdrops for the berries, add them right away as the fudge will set very quickly.
red, white, and green gumdrops
Chill in the refrigerator for 3-4 hours or until the fudge sets.
Serve fudge in small slices.
Store fudge covered either in the refrigerator or at room temperature.