Combine all ingredients in a large heavy-bottomed pot.
Bring to a boil over medium-high heat.
Reduce heat and partly cover. Simmer, stirring regularly to ensure nothing is sticking to the bottom and burning, for approximately twenty minutes until mixture becomes thick and glossy.
Remove from heat, let cool. Transfer to jars or other fridge- and freezer-safe containers.
Pumpkin butter can be stored, covered, in the fridge for a couple weeks or in the freezer for a few months.