Preheat the oven to 350°F (175°C) and lightly grease a large donut pan with cooking spray.

In a medium bowl, whisk together the pumpkin puree, olive oil, melted butter, vanilla extract, eggs, brown sugar, and granulated sugar until smooth.

Add the flour, pumpkin pie spice, baking powder, and salt to the wet ingredients. Stir until just combined; avoid overmixing.

Transfer the batter into a piping bag or a plastic bag with a corner snipped off. Pipe the batter into the prepared donut pan, filling each cavity about 3/4 full.

Bake for 25 minutes or until a toothpick inserted into the center comes out clean. Let the donuts cool in the pan for 10 minutes before transferring them to a cooling rack.

For the coating, mix the granulated sugar and cinnamon in a shallow container.

Once the donuts are completely cool, brush each with melted butter, ensuring full coverage. Dip each donut into the cinnamon sugar mixture to coat evenly.