Preheat the oven to 350 degrees F, and thoroughly grease two doughnut pans. Set aside.

Combine the dry ingredients, flour through nutmeg in a medium mixing bowl, and set aside. In a large bowl, whisk together the egg and brown sugar until combined. Add the buttermilk and yogurt. Finally, add the butter and vanilla extract, and whisk until all the wet ingredients are smooth. Add the dry ingredients to the wet, and combine with a spatula.

Transfer the batter to a large ziplock bag or pastry bag. Cut a small hole in the corner of the bag, and pipe the batter into the doughnut pans, filling each well about 3/4 full. Bake 8-10 minutes, or until the edges are slightly browned and a toothpick comes out with moist crumbs. Allow to cool for a few minutes, and then transfer to a cooling rack.

For The Glaze:

Combine the ingredients in a small mixing bowl, and allow to sit for about 5 minutes. Give the glaze another stir, and then dip each doughnut into the glaze. If you like a thicker glaze, allow the glaze to dry on each doughnut and then dip again!