Preheat the oven to 350°F (175°C). Lightly grease a donut pan (12-cavity if you have two six-cavity pans) with nonstick spray.
In a large bowl, whisk together the flour, granulated sugar, brown sugar, baking powder, baking soda, salt, cinnamon, nutmeg, ginger, and cloves until well combined.
In a separate bowl, mix the pumpkin purée, eggs, buttermilk, oil, and vanilla until smooth.
Pour the wet ingredients into the dry ingredients. Stir with a spatula until just combined. Do not overmix; a few small lumps are okay.
Spoon the batter into a large zip-top bag or piping bag.
Snip the corner and pipe the batter into the donut pan wells, filling each about 3/4 full.
Bake for 9–11 minutes, or until the donuts spring back when touched and a toothpick comes out clean.
Cool in the pan for 5 minutes, then gently turn out onto a wire rack.
For Cinnamon Sugar: Stir sugar and cinnamon in a shallow bowl. Brush warm donuts with melted butter and toss in the cinnamon sugar to coat.
For Maple Glaze: Whisk powdered sugar, maple syrup, a splash of milk, and a pinch of salt until smooth and pourable. Dip the tops of cooled donuts, let excess drip, and set on a rack to firm up.
Serve slightly warm for the best texture and flavor.