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.
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 pot from the heat. Add in the nuts and marshmallows and stir until mixed in well.
Spoon 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.
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.