Preheat oven to 350°F and lightly grease your donut pan with baking spray.
In a large mixing bowl, add milk, canned pumpkin, egg, granulated sugar, brown sugar, melted butter, and vanilla extract. Mix until smooth. Set aside.
In another bowl, sift together your flour, baking soda, cinnamon, nutmeg, cloves and cardamom.
Add the dry mixture to the wet mixture and gently fold together until just combined. Don't worry if there are little lumps of flour, they will dissolve when it bakes.
Using a spatula, fill your pastry bag with the dough. Cut an index finger diameter tip from the bag and fill your donut pan 1/2 of the way through. I made two circles to achieve this in my pan.
Bake for 10-12 minutes on the middle rack until a toothpick comes out clean. When baked, remove and transfer donuts to a cooling rack to cool completely.
While cooling, combine your granulated sugar and cinnamon together in a small bowl. Set aside while you melt the butter over low heat.
Using a pastry brush, brush the donuts lightly with the melted butter and then dredge them in the cinnamon sugar mixture. Return to cooling rack to set.
Eat and store on the counter in a non-air tight container. These donuts do get a little moist after day 2 so hurry up and eat them before then.