Line a standard loaf pan with parchment paper or wax paper.* Set aside. Clear some space in the freezer for this pan—you will need it later.
To make the fudge, use the double boiler method or the following: Add peanut butter and chocolate chips to a medium, microwave-safe bowl. Heat in 20-second increments until chocolate is softened and melty. Stir in between heating, until smooth.
Pour this mixture into the prepared loaf pan. Using a rubber spatula, smooth into an even layer.
Transfer pan to freezer. Freeze for about 1 hour, until solid. Remove from freezer and slice into 18 squares. Enjoy! Storing instructions below.