Line an 8 x 4 inch loaf pan with parchment paper, leaving some overhang on the sides for easy removal later. For thicker fudge, use a 7 inch loaf pan.
Add white chocolate chips to a microwave-safe bowl. Heat in 15-30 second increments, stirring in between with a spatula, until it’s completely smooth and melted. Alternatively, you can also melt the chocolate on the stove using the double boiler method.
Stir in the pumpkin puree with a spatula until the batter is smooth and uniform in color. Make sure your pumpkin is room temperature before adding it. If it has been in the fridge, it will cause the melted chocolate to seize.
Pour mixture into the prepared loaf pan and spread in an even layer. Cover with plastic wrap and freeze until the surface feels firm to the touch.
Once the fudge is set, remove the pan from the freezer. Lift the fudge out of the pan using the parchment paper overhang and place it on a cutting board. Cut into 1-inch squares with a large sharp knife. Serve immediately, or store them in an airtight container in the freezer until ready to eat.