In a medium saucepan, combine pumpkin purée, maple syrup, brown sugar, lemon juice, pinch of salt, and pumpkin spice. Stir until smooth.
Place over medium-low heat. Stir often and cook until mixture begins to thicken, about 20–30 minutes. Use a splatter guard if needed.
Continue cooking until the pumpkin mixture has a silky texture and darkens slightly. It should resemble pumpkin pie filling.
Remove from heat and stir in vanilla extract.
Transfer the pumpkin butter into a half-pint mason jar or small jars. Let cool before sealing with an airtight lid.
Store in the fridge for up to 2 weeks.