Instructions:
Step 1: In a medium bowl, whisk together flour, baking powder, salt, and nutmeg. Set aside.
Step 2: In a large mixing bowl, beat the sugar and butter until sandy. Add the egg yolks and beat until light and thick.
Step 3: Add the sour cream and vanilla extract, mixing until smooth. Gradually add the dry ingredients and mix just until combined.
Step 4: Cover the dough with plastic wrap and chill in the refrigerator for at least 1 hour.
Step 5: On a floured surface, roll out the dough to about 1/2-inch thickness. Use a donut cutter to cut out donuts and holes.
Step 6: Heat oil in a deep fryer or heavy-bottomed pot to 325°F (165°C). Fry the donuts in batches for 2-3 minutes per side or until golden brown.
Step 7: Remove and drain on a wire rack with paper towels underneath.
Step 8: For the glaze, whisk together powdered sugar, milk, and vanilla until smooth. Dip warm donuts in the glaze and let them set on the rack.
Storage Information:
Store cooled donuts in an airtight container at room temperature for up to 2 days. For longer storage, freeze unglazed donuts and glaze after reheating in the oven or air fryer.