Line a 8x8” pan with parchment paper, leaving some excess on 2 sides for easy removal of fudge.
In a microwave safe glass bowl melt the chocolate and water in 30 second pulses. Remove and stir. Microwave for another 30 seconds. Remove and stir again until melted and smooth. Do this for both the white and pumpkin spice chips, but in separate bowls.
Add your chopped nuts and dried cranberries to the white chocolate and stir. Next add the marshmallows and stir to mix thoroughly. Quickly add the pumpkin spice chocolate and fold in to create a swirl, being careful not to mix to much.
Pour and spread the white chocolate mixture evenly into the parchment lined pan. Refrigerate for 1 hour minimum, or until ready to serve. Allow to sit out for 5 minutes prior to cutting. Lift from pan using parchment paper and cut into 16 squares.
If pumpkin spice chips aren't available, substitute an equal amount of white chocolate chips plus 1/8 tsp pumpkin extract. Feel free to add a drop or two of gel food coloring for color, if desired.