Preheat the oven to 350°F (177°C). Grease a 9-inch pie pan with non-stick cooking spray. You can also use a slightly smaller 9 inch pie pan. See note section for more details.
Add all ingredients to a blender. (If adding pumpkin pie spice, add it at this time). Blend on medium speed for about 15-20 seconds until everything is mixed. You can also use a food processor but it may take slightly longer.
Pour batter into your prepared pie pan.
Bake for about 40-50 minutes or until the center of the pie is set. Let pie cool for about 30 minutes at room temperature. Then place into the fridge to cool and set for a few hours before cutting. If desired, you can decorate the surface of the pie with whipped cream or Cool Whip before serving. I piped homemade whipped cream and sprinkled some cinnamon on top.
