Step 1

Place 1 stick unsalted butter in the bowl of a stand mixer (or large bowl if using an electric hand mixer). Place 1 large egg and 1/2 cup sour cream on the counter. Let everything sit at room temperature until the butter is softened.

Step 2

Meanwhile, place 1 3/4 cups all-purpose flour, 1/2 teaspoon baking powder, and 1/4 teaspoon baking soda in a medium bowl and whisk to combine.

Step 3

Arrange 2 racks to divide the oven into thirds and heat the oven to 350°F. Line 2 baking sheets with parchment paper or silicone baking mats.

Step 4

Finely grate the zest from 1 medium lemon (about 1 tablespoon) and juice the lemon until you have 2 tablespoons.

Step 5

Add the lemon zest and 3/4 cup granulated sugar to the butter. Beat with the paddle attachment on medium speed until combined and creamy, about 2 minutes, stopping and scraping the sides of the bowl down with a flexible spatula as needed.

Step 6

Add the egg, sour cream, lemon juice, 1/2 teaspoon kosher salt, and 1/2 teaspoon lemon or vanilla extract. Beat on medium speed until combined, about 30 seconds. The mixture may look curdled. Add the flour mixture and beat on the lowest speed until just combined, about 1 minute.

Step 7

Scoop the dough out into level tablespoon-sized portions (about and place 1 1/2 inches apart on the baking sheet, 12 cookies per baking sheet.

Step 8

Bake until the edges of the cookies are set and the centers are puffed, about 10 minutes. Let cool on the baking sheet for 2 to 3 minutes, then transfer to a wire rack to cool completely. Repeat baking with the remaining dough; you can reuse the hot baking sheets and parchment or baking mats. Lightly dust the cookies with 2 tablespoons powdered sugar before serving.