Preheat the oven to 325°F. Line a baking sheet with parchment paper and set it aside.

In a large mixing bowl, cream together the sugar and butter until well combined and fluffy. Mix in the egg and vanilla.

In a medium mixing bowl, whisk together the flour, baking powder, and salt.

Pour half of the flour mixture into the butter mixture and combine with a hand mixer until well combined. Add the remaining flour mixture to the butter mixture with a hand mixer, switching to a rubber spatula if necessary until everything is well combined.

Place the nonpareils in a small bowl.

Using a 1-1/2 cookie scoop or a little over a tablespoon, scoop out the cookie dough and roll each ball into the sprinkles until completely covered. Place the dough balls on the prepared baking sheet leaving about 1-1/2-inches between the cookies.

Bake for 10-12 minutes.

Remove the baking sheet from the oven and allow the cookies to cool on the baking sheet for 10 minutes before transferring them to a cooling rack to cool completely.