For the cookies:
4 cups cake flour
½ tsp baking powder
½ tsp salt
1 cup unsalted butter, at room temperature
1¾ cups granulated sugar
2 eggs, at room temperature
½ tsp vanilla extract
¼ tsp lemon extract
1 cup milk
For the icing:
2 oz unsweetened chocolate, finely chopped
⅓ cup water
¼ cup light corn syrup
5 cups powdered sugar
½ tsp vanilla extract
1) Adjust oven racks to lower-middle and upper-middle positions. Preheat oven to 375. Line two baking sheets with parchment paper or a silicone baking mat.
2) In a large bowl, whisk flour, baking powder and salt; set aside.
3) Beat butter at medium speed for 30 seconds to loosen it up. With the mixer running, gradually add sugar and gradually increase speed to medium-high. Beat until mixture is light and fluffy, about 3 minutes. Scrape down sides of the bowl and add the eggs, vanilla and lemon extract. Beat at medium speed until combined, about 30 seconds. Scrape down the sides and bottom of the bowl again.
4) With mixer on low speed, alternately add flour in four additions and milk in three additions, beginning and ending with flour, and mix until just combined. Give mixture a few final stirs with a rubber spatula to ensure flour has been incorporated.
5) Use a ¼-cup measuring cup to scoop mounds of dough onto prepared baking sheets, about two inches apart. With moistened fingers, gently press each mound of dough into a 2 and 1/2-inch circle. Bake until edges of cookies are set and light golden brown, about 20 minutes. Allow cookies to cool for 2 minutes on the baking sheets, then remove to a wire rack to cool completely.
1) Melt chocolate either in a medium bowl over a small saucepan of barely simmering water, or in a microwave on 50% power in 30-second increments. Set aside.
2) In a medium saucepan over medium heat, bring water and corn syrup to a boil. Remove from heat and whisk in powdered sugar and vanilla extract. Transfer ¾ cup of icing to the bowl with melted chocolate and whisk to combine.
1) Place wire racks over wax paper to catch any drips. Use a small offset spatula to spread about 2 tablespoons of vanilla icing onto half of each cookie. The icing should move on its own when the cookie is tilted; use spatula to scrape any excess from around the edges. If icing begins to thicken too much, stir in one teaspoon at a time of warm water until icing goes back to a smoother, looser consistency. Place finished cookies on wire racks and allow to set for at least 15 minutes.
2) Again using a small offset spatula, spread chocolate icing on the plain half of each cookie, scraping any excess from around the edges. If chocolate icing thickens too much, place bowl on a small saucepan of barely simmering water so that it can re-melt. If it’s still too thick, add warm water, one teaspoon at a time, until it returns to the correct consistency. Place finished cookies on wire racks and allow to set for at least 1 hour.
The cookies can be stored in an airtight container at room temperature for up to 3 days. If you stack the cookies, place wax paper between layers.