Mix pumpkin, spice, sugar, corn syrup and evaporated milk in large pan and cook over medium heat.
Sir occasionally.
Mixture will begin boiling. If it boils too close to top reduce heat slightly.
Continue cooking until mixture reaches soft ball stage (235-245 degrees). You can either use a candy thermometer or you can test for this by putting a few drops of the syrup in cold water. if it forms a ball in the water, but flattens once removed from the water - it is at the soft ball stage..
Remove from heat.
Unwrap the end of the stick of butter and use the butter to grease inside of glass 8"x8" baking dish.
Add remainder of the butter to the fudge mixture and stir until the butter is melted and the mixture start to lose its sheen.
Pour mixture in to buttered baking dish and allow to cool.
Cut in to squares