Preheat the oven to 350°F. Line 2 large baking sheets with parchment paper.
In a medium bowl, whisk the flour with the baking powder, salt, and nutmeg.
In a stand mixer fitted with the paddle, beat the butter with 1 ½ cups of the sugar at medium speed until light and fluffy, about 3 minutes.
Beat in the egg and vanilla until incorporated, about 1 minute.
At low speed, mix in the dry ingredients until just combined.
Spread the remaining ½ cup of sugar in a shallow bowl.
Scoop 2-tablespoon-size mounds of dough, roll them in the sugar, and place them on the prepared baking sheets, about 2 inches apart.
Bake the cookies for 12 to 14 minutes, until the edges are just set and lightly golden brown; rotate the sheets from top to bottom and front to back halfway through baking.
Let the cookies cool on the sheets for a few minutes, then transfer them to a wire rack to cool completely.
