In a large mixing bowl, combine the canned pumpkin puree, brown sugar, granulated sugar, ground cinnamon, ground nutmeg, ground ginger, ground cloves, and salt. Stir well to combine all the ingredients evenly.
Add the vanilla extract and lemon juice to the mixture, then mix again until fully blended.
Transfer the pumpkin mix to the Crock Pot, spreading it evenly across the bottom.
Cover the Crock Pot with its lid and set it to low heat. Cook for 8 hours, stirring occasionally.
After 8 hours, check the consistency. If it’s still a bit runny, cook for an additional hour uncovered to allow it to thicken.
Once done, allow the pumpkin butter to cool slightly before transferring it to clean storage jars.
Store in the refrigerator for up to 2 weeks or can it for longer shelf life.