Heat your oven to 350°F. Spray a regular-size donut pan with vegetable spray.
In a bowl, add the flour, brown sugar, pumpkin pie spice, cinnamon, salt, and baking powder. Stir to combine.
In a microwaveable bowl, place the vegan butter. Heat for 20–30 seconds, until the butter is melted. Add the pumpkin puree and plant-based milk. Stir to combine.
Pour the pumpkin mixture into the flour mixture. Stir until just combined (don't over mix).
Use a spoon or carefully pour the batter into the donut compartments, filling them generously and equally. Bake for approximately 15 minutes, until the donuts are done and slightly golden on the edges.
In the meantime, prepare the Cinnamon Sugar Topping by melting the vegan butter in one bowl. In a second bowl, combine the sugar, pumpkin pie spice, and cinnamon spice.
Once the donuts are done, remove from the oven and allow them to cool for a minute or two. Once they're cool enough to handle, dip the top part of each donut in the melted vegan butter, followed by a dip in the cinnamon sugar. Repeat with each donut. If you have enough melted butter and cinnamon sugar, repeat this process with the bottom half of each donut.