In a microwave-safe bowl, heat the chocolate in the microwave until smooth. Stir in sweetened condensed milk. Return to the microwave for another 30 seconds, stirring until smooth. Set aside to cool.

Place the marshmallow cream and peanut butter in a bowl. Heat in the microwave for 20 seconds, remove, and stir until smooth.

In the bowl of a stand mixer fitted with the whisk attachment, whip the heavy cream on high until stiff peaks form. Pour in the cooled white chocolate mixture and continue beating until incorporated.

Divide custard mixture among four bowls and dye each individually with desired colors. Spoon about 1/3 of the colored custards into an 8-inch baking pan, alternating between each color. Drizzle 1/3 of the fluffernutter mixture on top.* Repeat these steps twice more with the remaining custard and fluffernutter mixture.

Using a skewer or knife, swirl a few figure-8's throughout the pan.** Top with sprinkles. Wrap pan with plastic wrap and freeze for at least 8 hours or overnight.