Stir together pumpkin purée, apple juice, sugar, spices, and fine sea salt in a medium saucepan.

Bring to a boil. Reduce heat to low and simmer gently for 30-40 minutes, stirring frequently. The mixture will thicken slightly, and will darken in color.

Allow pumpkin butter to cool at room temperature for 30 minutes.

Store in an airtight container in the refrigerator for up to one week, or in the freezer for up to three months.