Preheat the oven to 400 degrees. Halve the pumpkin from top to bottom and scoop out the seeds and pulp. Set cut-side down on a baking sheet that has been sprayed with gluten-free cooking spray. Bake for 30 minutes, or until flesh is tender and pumpkin can be easily pierced with a knife. Cool for 10 minutes.
Scoop out the flesh from the pumpkin and puree until smooth using a stick blender, blender, or food processor. If you are using canned pumpkin obviously skip the last two steps.
Add the pumpkin puree to a medium saucepan, along with the sugars, apple juice, maple syrup, spices and salt. Simmer over low heat for about 30 minutes. The mixture will be thick.
Pour pumpkin butter into sterilized jars and refrigerate. Use within 3 weeks.