Line an 8-inch square pan with foil and grease the foil with butter or cooking spray; set aside.
In a large microwave-safe bowl, combine frosting, white chocolate chips, pumpkin, pumpkin pie spice, and salt. Cook in microwave until melted and smooth. Microwaves vary, but I cooked mine for about 1 minute, 30 seconds total (stirring every 30 seconds).
Cool for about 5-10 minutes.
Stir in cinnamon chips.
Transfer to prepared pan.
Cover and refrigerate until firm.
Using foil, lift fudge out of pan. Discard foil, cut into 1-inch squares. Store in an airtight container in the refrigerator.