Preheat your oven to 375°F (190°C) and grease a donut pan with non-stick spray.
In a large mixing bowl, whisk together the flour, granulated sugar, brown sugar, baking powder, baking soda, salt, cinnamon, and nutmeg until well combined.
In another bowl, whisk together the eggs, buttermilk, melted butter, and vanilla extract until smooth.
Pour the wet ingredients into the dry ingredients and gently mix until just combined; do not overmix. The batter will be thick.
Transfer the batter to a piping bag or a large zip-top bag and cut a small hole at one corner. Pipe the batter into the prepared donut pan, filling each cavity about 2/3 full.
Bake in the preheated oven for 10-12 minutes, or until the donuts are golden brown and a toothpick inserted into the center comes out clean.
Allow the donuts to cool in the pan for 5 minutes, then transfer them to a wire rack to cool completely.
While the donuts are cooling, prepare the glaze by whisking together the powdered sugar and maple syrup in a mixing bowl until smooth. Adjust the consistency with more maple syrup or powdered sugar as needed.
Once the donuts are cool, dip the top of each donut into the glaze, allowing any excess to drip off.
Place the glazed donuts on the wire rack to let the glaze set for a few minutes.