1. In a medium sized bowl, whisk to combine the flour, baking powder, salt, cinnamon and nutmeg. Set aside. 
2. In the bowl of an electric mixer,  beat the butter and sugar together until well combined. With the mixer running, add the vanilla and the egg yolks. Turn the mixer to low and add the sour cream alternatively with the dry ingredients.
3. Cover the bowl with plastic wrap and refrigerate for one hour. While the dough chills, mix the glaze together. (If the glaze has hardened a bit when you’re ready to use it, just pop it in the microwave for about ten seconds then stir to smooth it out). 
4. Once chilled, turn the dough out onto a lightly floured surface. Fold the dough over on itself to smooth it out a little. Use a rolling pin to roll the dough into 1/2 inch thickness. Dip your donut cutter in a small bowl of flour to prevent sticking and cut out as many donuts as possible. Reroll out dough if needed. Place donuts on a parchment or wax paper lined baking tray and place tray in the fridge to chill donuts for at least 15 minutes. 
5. While donuts chill, gather what you need for frying. Line a plate, cutting board or baking tray with paper towels. Take out a spider strainer and/or tongs.
6. Fill a large pot with a heavy bottom with about 2 inches of oil. Heat oil to 340 degrees F. Use tongs to carefully drop 2-4 donuts in the hot oil. Fry for 1- 1 1/2 minutes per side until donuts are golden brown. Transfer donuts to paper towel lined plate to cool slightly. Use the thermometer to check the temperature of the oil again (temperature will drop after  adding donuts, make sure it has come back up to 340 F). Continue frying the remaining donuts and donut holes. Donut holes will take less time to fry. 
7. Dip warm donuts in the glaze and flip to cover both sides. Place donuts on a cooling rack to allow the glaze to slight slightly. Enjoy while still warm or once cooled! 

FOR THE POWDERED SUGAR GLAZE

1. In a medium sized, microwave safe bowl,* whisk to combine the powdered sugar, melted butter and vanilla. Add the hot water a tablespoon at a time until you reach the consistency you desire.