Instructions

• Preheat oven to 350°F (175°C). Line a baking sheet with parchment paper or a silicone baking mat.
• In a small bowl, whisk together 3/4 cup + 2 tablespoons (105 g) all-purpose flour, 1/2 teaspoon baking powder, and 1/4 teaspoon salt. Set aside.
• In a medium bowl, use a handheld electric mixer (optional but helpful) or a wooden spoon to cream 1/3 cup (76 g) softened unsalted butter and 1/4 cup + 2 tablespoons (75 g) granulated sugar until light and fluffy, about 1 to 2 minutes.
• Add 1 large egg white and 1/2 teaspoon vanilla extract to the creamed butter and sugar. Beat until well combined.
• Add the flour mixture to the wet ingredients and mix just until incorporated. The dough will be fairly soft and sticky.
• If using, place 1/3 cup (40 g) powdered sugar in a small bowl for rolling. Using a spoon or small cookie scoop, drop a 1 1/2-ounce spoonful of dough into the powdered sugar, toss to coat, and roll into a ball. If not using powdered sugar, drop the same-sized spoonfuls of dough directly onto the prepared baking sheet. Repeat with the remaining dough (this should make 6 cookies).
• Arrange the dough balls on the prepared baking sheet with space between them for spreading.
• Use the palm of your hand or the bottom of a flat-bottomed glass to gently press each dough ball until each is about 1/2 inch thick.
• Bake for 9 to 12 minutes, until the cookies look set and the bottoms are lightly golden. Do not overbake.
• Let the cookies cool on the baking sheet until they are cool enough to handle, then transfer them to a wire cooling rack. Cool completely before frosting.
• For the frosting, in a medium bowl beat 3 tablespoons (1.5 oz) softened unsalted butter until fluffy.
• Add 3/4 cup (90 g) sifted powdered sugar, 1 teaspoon of the milk or cream, 1/4 teaspoon vanilla extract, and a pinch of salt. Beat until smooth.
• Add additional milk or cream by 1/4-teaspoon increments (up to the remaining portion of the 1–2 teaspoons total) until the frosting reaches your desired spreading consistency. Add a couple drops of food coloring if desired.
• Use a knife or an offset spatula to spread the frosting onto the cooled cookies. Top immediately with sprinkles if desired.