Birthday Cake Style Fudge

3 cups sugar
1 1/2 sticks margarine
5 oz can (2/3 cup) evaporated milk
12 oz chopped white chocolate (I used white chocolate chips)
7oz jar marshmallow creme
3 Tablespoons yellow cake mix (just the powdered MIX, not batter)
1 teaspoon vanilla
Blue candy coloring
Rainbow sprinkles

Line a 9 inch square pan with foil, with the ends hanging over the edges of the pan. Spray foil thoroughly with nonstick spray.

Place the sugar, margarine, and evaporated milk in a heavy saucepan over medium heat. Bring to a full rolling boil, stirring constantly, and let boil for exactly 4 minutes. Remove from heat.

Add chocolate chips, marshmallow creme, and cake mix, stirring until chocolate chips are melted. Add vanilla and mix well.

Working as quickly as possible, pour about 1/3 of the fudge in a bowl and add a few drops of blue candy coloring, mixing and adding until you achieve the desired shade. Pour white fudge into prepared pan, spreading evenly. Spoon blue fudge over the top, spacing it out. Using a sharp knife, draw swirls through the blue and white to create a marbled effect. Sprinkle the top generously with rainbow sprinkles before the top sets up.

Let store at room temperature until cool, then place in the refrigerator until firm.