Preheat your oven to 350°F (175°C).
Grease a donut pan with cooking spray or butter.
In a large bowl, whisk together the flour, sugar, baking powder, baking soda, cinnamon, nutmeg, and salt.
In a separate bowl, whisk together the melted butter, buttermilk, eggs, and vanilla extract. Add the apple cider and mix until well combined.
Pour the wet ingredients into the dry ingredients and stir until just combined. Be careful not to overmix; a few lumps are okay.
Spoon the batter into a piping bag or a Ziploc bag with the corner cut off. Pipe the batter into the prepared donut pan, filling each mold about 2/3 full.
Bake in the preheated oven for 12-15 minutes or until a toothpick inserted into a donut comes out clean.
While the donuts are baking, mix the sugar and cinnamon in a shallow bowl. Once the donuts are done, let them cool for a few minutes. While they're still warm, gently roll each donut in the cinnamon-sugar mixture to coat it evenly.
