I do not always post recipes because I eyeball a lot of the ingredients rather than measuring. Here is the recipe I used and I will tell you what I did differently.
Recipe adapted from http://www.shutterbean.com/2013/baked-cinnamon-sugar-doughnuts/
1 cup all-purpose flour
3/4 cup sugar
1 teaspoon baking powder
1/2 teaspoon ground cinnamon (I ONLY HAD SUGAR MIXED WITH CINNAMON)
1/4 teaspoon freshly grated nutmeg (I DID NOT HAVE ANY SO I DID NOT USE ANY)
1/4 teaspoon kosher salt (I USED REGULAR SALT)
1 extra-large egg, lightly beaten
1/2 cup buttermilk (I DID NOT HAVE ANY SO I USED SOUR CREAM AND ALSO ADDED 1/2 A TEASPOON OF VINEGAR)
2 tablespoons unsalted butter, melted
1 teaspoons vanilla extract
For the topping
4 tablespoons (1/2 stick) unsalted butter, melted
1/2 cup sugar
1 teaspoon ground cinnamon
For the donuts: Preheat the oven to 350 degrees. Use a baker’s spray to coat doughnut pan.
Sift together the flour, sugar, baking powder, cinnamon, nutmeg and salt in a mixing bowl.
Whisk together the egg, milk, melted butter and vanilla extract in a medium bowl or liquid measuring cup. Pour into the dry ingredients and stir until just combined.
Fill the wells of the doughnut pans a bit more than three-quarters full with the batter. Bake for 15-17 minutes or until a toothpick inserted into the wall of a doughnut comes out clean and the doughnuts are puffed and lightly browned. Let them cool (in the pan) for 5 minutes, then gently invert the doughnuts onto a rimmed baking sheet.
While the doughnuts are cooling, make the topping.
Whisk together the sugar and cinnamon in a medium bowl.
Brush the warm doughnuts with the melted butter, then dip them into the cinnamon-sugar mixture on one or both sides. Serve warm.