1. In a medium bowl, sift together flour, salt, baking powder, and nutmeg. Set aside.
2. In the bowl of an electric mixer fitted with the paddle attachment, cream sugar and butter together until sandy. Add egg yolks and mix on medium speed until pale and fluffy.
3. Turn speed to low, and alternate adding the flour mixture with the buttermilk, ending with the flour. Stop the mixer and scrap down the sides as needed.
4. Wrap the dough in plastic wrap (it should be sticky) and flatten into a disk. Chill for one hour.
5. Pour two inches of oil into a large, heavy bottomed pot. Using an oil thermometer, bring the temperature to 350-375 degrees.
6. While you are waiting for the oil, roll out your dough (3/4 inch thick) onto a well-floured surface. Dip your donut cutter (2 1/2 inches in diameter) in flour and cut out donuts, gathering and re-rolling the dough as needed.
7. Carefully and slowly drop a few donuts at a time into the hot oil. Fry about 1 minute per side, aiming for a pale golden-brown color.
8. Use a slotted spoon or spatula to remove the donuts from the pot and set onto a paper towel to drain. Repeat until all the dough is fried. The donut holes will only take about 1 minute total.

For the Glaze

1. Whisk all ingredients together in a bowl until smooth. Dip cooled donuts into the glaze, covering the whole surface of the donut and then set them on a rack so that excess glaze will drip off. Allow the glaze to set for 20-30 minutes. Store in an airtight container.