Step 1
Line an 8 x 8-inch pan with parchment paper and grease with vegetable oil. Leave some parchment paper overhanging from the sides of the pan for easy removal.
Step 2
Combine both sugars, pumpkin, butter, evaporated milk, spice, vanilla, and salt in a medium saucepan. Bring mixture to a boil over medium heat, stirring constantly. Boil until a candy thermometer reaches 235-245°F (soft-ball stage).
Step 3
Remove mixture from heat and immediately stir in white chocolate chips. Stir until all the chocolate melts. Pour onto prepared pan and allow to cool completely, about 2 hours. Cover with plastic wrap and refrigerate for at least 8 hours.
Step 4
Remove fudge from the refrigerator and let stand until it reaches room temperature. Lift from pan and carefully cut into 16 even pieces.
Add 1 cup of chopped pecans at the same time you add the white chocolate chips to add an extra layer of flavor and texture.