Ingredients

3 c. all-purpose flour

1/2 tsp. baking soda

1/2 tsp. baking powder

1/2 tsp. salt

1 3/4 stick butter

1 1/4 c. sugar

2 large eggs

1 large egg yolk

3/4 c. buttermilk

1 tbsp. pure vanilla extract

1 tbsp. freshly grated lemon zest

4 c. confectioners’ sugar

1/4 c. milk

3 tbsp. heavy cream

2 tsp. pure vanilla extract

Red no-taste gel food coloring

Preparation

Step 1To make cookies: Preheat oven to 350 degrees. Sift flour, baking soda, baking powder, and salt into a large bowl.Step 2In the bowl of an electric mixer fitted with a paddle attachment, cream butter and sugar until fluffy (about 2 minutes). Scrape down the bowl and add eggs and egg yolk one at a time, beating briefly after each addition. Scrape down the bowl again, and turn mixer to low. Add the flour mixture in 3 parts, alternating with the buttermilk in 2 parts. Scrape down the bowl; add vanilla and lemon zest, and mix on low speed for a few more seconds.Step 3Using an ice cream scoop (about 1/4 cup), drop dough onto parchment-lined baking sheets spaced about 3 inches apart (6 cookies per sheet).Step 4Bake for 17 minutes, rotating sheets between oven racks halfway through, until edges are golden brown and tops spring back when gently touched. Remove from oven and let sit for 5 minutes, then remove cookies and cool on racks.Step 5To make frosting: In a large bowl, whisk together confectioners’ sugar, milk, and cream. If mixture is too thick, add a little more milk (by the teaspoon until desired consistency is reached). Pour half of the frosting (about 3/4 cup) into another bowl and add vanilla and red food coloring until desired red color is reached.Step 6Use an offset spatula to spread red frosting on half of the top of each cookie. Let stand until almost set, 20 minutes. Using a clean spatula, spread white frosting over unfrosted half of each cookie. (If the frosting thickens up during the process, whisk until loose.) Let set completely, about 1 hour.