In a mixing bowl, combine the flour, baking powder, salt and nutmeg.

In the bowl of a stand mixer or using a hand mixer, beat the butter and sugar together on medium speed for 1 minute.

Beat in the egg and egg yolk on medium speed for 2 minutes.

Beat in the buttermilk and vanilla extract.

Gradually add the dry ingredients, mixing on low speed until fully combined.

Cover the bowl with plastic wrap and refrigerate for at least 1 hour, until firm and not tacky. The dough can be stored like this for up to 24 hours.

Lightly flour the dough and your work surface, then roll out the dough to ½-inch thickness.

Dip a 3-inch round cookie or biscuit cutter in flour and use it to cut circles from the dough. Then, cut a hole in the center of each circle with a 1 ¼-inch round cutter (you can also use the large end of a piping tip). Arrange the donuts and donut holes on a tray lined with parchment paper or a silicone mat. Place the donuts in the refrigerator while you heat the oil.

Pour oil into a large, heavy-bottomed pot to a depth of 2 inches. Heat over medium heat until a deep-fry or candy thermometer reads 325°F. Line a large baking sheet with paper towels.

Gently add 2 to 3 donuts to the hot oil at a time. Fry for 2 minutes, allowing the donuts to sink initially before they float to the surface (this should happen within 5 to 10 seconds). Flip the donuts and fry for an additional 2 minutes. Use a slotted spoon or strainer to remove the donuts and place them on the prepared baking sheet to drain. Adjust the heat as needed to maintain the oil temperature at 325°F. Fry donut holes for about 30 seconds per side.

In a microwave safe bowl, combine the chocolate chips, butter and corn syrup. Microwave on 50% power for 60-90 seconds until fully melted.

Transfer the glaze to a shallow dish. Dip one donut at a time into the glaze, allowing the excess to fall off into the bowl. Allow the donuts to set for 1-2, then add sprinkles. I allowed my donuts to cool for 30 minutes after frying and before glazing.

In a small bowl, combine the powdered sugar, milk, and vanilla extract until pourable. Add more powdered sugar if it’s too runny or more milk if it’s too thick.

Transfer the glaze to a shallow dish. Dip one donut at a time into the glaze, allowing the excess to fall off into the bowl. I allowed my donuts to cool for 30 minutes after frying and before glazing.