Line an 8x8 square baking pan with parchment paper, making sure that you use a big enough piece that it overhangs the sides.
In a double boiler on the stovetop, on medium-low heat, place the white chocolate chips into the bowl along with the vanilla frosting.
Stir the white chocolate chips and vanilla frosting every couple minutes to evenly melt chocolate chips without allowing them to burn. It will take between 8 to 10 minutes to get your white chocolate completely melted and smooth.
Using 2 additional bowls, divide your melted chocolate and frosting into 3 equal portions. Add the red gel food coloring to the first bowl and stir until completely blended.
Repeat with the green gel food coloring in the second bowl. Your third bowl will remain plain white.
Using a large spoon dollop 2 tablespoons full of each of the colors randomly in the prepared pan. Once all the melted chocolate is in the pan, take a butter knife and swirl the colors around to make a pretty swirl pattern.
Place the pan of Christmas Fudge into the refrigerator, uncovered, for 1 to 2 hours to firm up and set.
Remove the fudge from the tray by lifting it out with the overhanging parchment paper. Slice into pieces and serve.