Preheat the oven to 350 degrees.
In a medium bowl, mix together all the dry ingredients (flour, baking soda, baking powder, salt, ground nutmeg, and cinnamon)
In a bowl with a stand mixer, beat the butter, sugar, and brown sugar. Beat until light and fluffy for about 3 minutes.
Add in the eggs one by one and the vanilla and beat on low until fluffy.
Add in the buttermilk, sour cream, and apple cider and mix until just combined.
Add the dough to a piping bag and grease the donut pan with butter.
Pipe the donut dough into the donut pan about 2/3 of the way full.
Bake the donuts for 10-12 minutes until fully cooked in the center.
After the donuts are cool, melt the butter, brush the butter on top and dip into the cinnamon sugar mixture.