Line an 8-inch square baking dish with parchment paper.
In a medium saucepan over low heat, combine the sweetened condensed milk and butter, stirring until smooth and melted.
Add the pumpkin puree and spices to the melted mixture, stirring continuously on low heat until fully incorporated.
Gradually add the chocolate chips to the mixture, stirring continually until fully melted.
Pour the fudge mixture into the prepared dish, spreading evenly with a spatula.
Refrigerate for about 2 hours or until fully set.
Lift the fudge out using the parchment paper and cut into squares.
Store in an airtight container in the refrigerator for up to two weeks.