Preheat oven to 425° F and line a baking sheet with unbleached parchment paper. Place pumpkin half on the baking sheet, cut side down. Roast on the middle rack in the oven for about 40 minutes, until pumpkin is cooked all the way through and very soft. Remove baking sheet from the oven and let cool for about 5 minutes.
Scoop the pumpkin out of the skin and place into a mixing bowl. Add the banana and pumpkin pie spice. Blend until smooth using an immersion blender. You can also blend using a food processor or standard blender.
Serve or store. Pumpkin Pie Puree will stay fresh in an airtight container, like our glass Sage Spoonfuls jars, for up to three days in the fridge and up to three months in the freezer.