Step 1

In a medium bowl, sift the dry ingredients - cake flour, baking powder, nutmeg, and kosher salt.

Step 2

In a separate large mixing bowl, use a hand mixer to beat together room temperature butter. Beat butter for 2 minutes, then add the sugar and continue to mix for 3 minutes. Add egg yolks and vanilla extract mix until combined, about 2 minutes.

Step 3

Add half of the sour cream, then add half of the flour mixture. Use a flat spatula to mix the flour into the dough. Then add remaining sour cream and flour. Dough should be slightly firm, mix until all of the flour and sour cream are fully incorporated.

Step 4

Cover with plastic wrap and store in the refrigerator for one hour up to overnight, until firm.

Step 5

Add fry oil to a large pot or dutch oven. Heat the oil to 350 degrees F. Roll donut dough out onto a generously floured surface. Use a rolling pin to roll dough out until it's a 1/2 inch thickness. Use 3 inch biscuit cutters or donut cutters to cut donuts into the dough. Then cut a small circle in the center of the donut (Pro tip: I use the cap of a soda bottle, it's the perfect size) Re-roll the dough and repeat until all of the dough is used.

Step 6

Place donuts onto a baking sheet and refrigerator uncovered for 20 minutes. Then add to hot oil, 2-3 donuts at a time, frying on each side for about 2-3 minutes each side until deep golden brown. Remove donuts from the frying oil and place onto a wire rack or paper towel to remove any excess oil.

Step 7

While the donuts are cooling, make the glaze by combining powdered sugar, corn syrup, warm milk, and vanilla extract in a large bowl. Whisk together.

Step 8

Once the donuts have cooled, dip both sides of the donut into the glaze and place on the cooling rack so that the glaze can set.