Beat 1 stick room temperature unsalted butter, ½ cup granulated sugar, and ½ teaspoon kosher salt together with the paddle attachment on medium speed until light and fluffy, about 2 minutes. Scrape down the sides of the bowl.

Beat in 3 room temperature large eggs on medium speed one at a time, waiting until each is incorporated before adding the next. Beat in 2 teaspoons almond extract until combined.

Sprinkle 2 teaspoons baking powder evenly over the butter mixture. Add 2 ¼ cups all-purpose flour and beat on the lowest speed just until a sticky dough forms, 30 to 45 seconds.

Cover and refrigerate for 1 hour to firm up. About 20 minutes before the dough is ready, arrange 2 racks to divide the oven into thirds and heat the oven to 350°F. Line 2 rimmed baking sheets with parchment paper.

Scoop out 1-tablespoon portions of the dough onto one of the baking sheets. Roll each one into a ball and arrange on both baking sheets about 1 ½ inches apart, up to 24 cookies per sheet.

Bake for 8 minutes. Rotate the baking sheets from top to bottom and front to back. Continue to bake until the cookies are starting to crack on top and turning light golden brown on the bottom, 5 to 6 minutes more. Let cool on the baking sheets for 5 minutes. Transfer the cookies to wire racks and let cool completely.

Whisk 1 ⅓ cups powdered sugar, 3 tablespoons milk, ½ teaspoon almond extract, and ¼ teaspoon kosher salt together in a medium bowl until smooth.

Dip and decorate the cookies in batches of 10: Dip the top of a cookie in the glaze and keep the cookie upside down while gently shaking so excess glaze drips back into the bowl. Return the cookie to the rack, glaze-side up. Dip the next 9 cookies, then sprinkle with nonpareils. Let sit until the glaze sets, about 20 minutes.