In a stand mixer, cream the butter and sugar together.

Add the egg and vanilla and beat on medium speed until mixed well, scraping the sides as needed.

Add the flour and nutmeg.

Mix just until combined (scraping down the sides once). Be careful not to overmix.

Form the dough into a thick log (about 8-10" long. Press the log tightly together so that there are no air pockets in the cookie dough.

Place a long sheet of plastic wrap on the counter or table.

Place sprinkles on the plastic wrap.

Roll the cookie dough log in the sprinkles until it is completely covered, adding more as needed.

Wrap the dough in the plastic wrap and refrigerate the dough for at least 2 hours.

Heat the oven to 325 degrees.

Remove the cookie dough from the refrigerator and unwrap it.

Using a sharp knife, cut slices off the cookie dough log. Cut the slices 1/4" thick or a little less.

Place the cookie dough slices on a baking sheet with a silicone mat (or lightly grease the cookie sheet).

Bake for 10-12 minutes, or just until the cookies are set. Don't allow them to brown.

Allow the cookies to cool for 3-5 minutes on the baking sheet, then remove them to wire racks to cool completely.

Store in an airtight container.