Preheat your oven to 350°F (175°C). Grease your donut pan with non-stick spray or a light coating of butter.
In a small saucepan, melt the 2 and 1/2 tablespoons of unsalted butter over medium heat until golden brown.
In a medium mixing bowl, whisk together the all-purpose flour, salt, baking powder, and ground nutmeg.
In a large mixing bowl, combine the brown sugar, egg, vanilla extract, and whole milk. Add the browned butter and whisk until smooth.
Gently fold the dry mixture into the wet ingredients until just combined.
Fill each cavity of the donut pan about 2/3 full with batter.
Bake for 10-12 minutes, or until a toothpick comes out clean.
While the donuts are baking, mix the granulated sugar and ground cinnamon in a shallow bowl.
Let the donuts cool for 5 minutes in the pan, then transfer to a cooling rack. Roll each donut in the cinnamon sugar mixture.
Enjoy your warm Baked Cinnamon Sugar Donuts!
