Combine all ingredients in a saucepan. Whisk until smooth.
Simmer on medium-low heat for 10 minutes, whisking often. Cool.
Use right away or pour into jars and store in a fridge for up to 2 weeks.
Notes
Make sure you are not using pumpkin pie filling. The label should read "100% pumpkin puree".
Dark brown sugar will add rich, deeper flavor to the butter. However, light brown sugar works too. You can add 1 tablespoon of molasses if using light brown sugar.
Please note, that the nutrition value can vary depending on what product you use. The information below is an estimate. Always use calorie counter you are familiar with.