2 1/2 c cake flour
1 tsp baking powder
1/2 tsp baking soda
1/2 tsp salt
3/4 c buttermilk, room temperature
3 Tbsp grated zest and ¼ cup juice from 3 lemons
1 tsp vanilla extract
1 3/4 c granulated sugar
1 1/2 stick unsalted butter, softened
3 large eggs plus 1 egg yolk, room temperature
3 c confectioners’ sugar
3 Tbsp lemon juice
2 Tbsp buttermilk
1. Adjust oven rack to middle position and heat oven to 325 degrees. Grease and flour 13 x 9 inch baking pan.
2. Combine flour, baking powder, baking soda, and salt in medium bowl. Combine buttermilk, lemon juice, and vanilla in liquid measuring cup.
3. With electric mixer on medium speed, beat granulated sugar and lemon zest until moist and fragrant, about 1 minute. Transfer ¼ cup sugar mixture to small bowl, cover, and reserve.
4. Add butter to remaining sugar mixture and beat until light and fluffy, about 2 minutes. Beat in eggs and yolk, one at a time, until incorporated. Reduce speed to low. Add flour mixture in 3 additions, alternating with 2 additions of buttermilk mixture, and mix until smooth, about 30 seconds. Scrape batter into prepared pan and smooth top.
5. Bake until cake is golden brown and toothpick inserted into center comes out clean, 25 to 35 minutes. Transfer cake to wire rack and let cool 10 minutes.
6. For the glaze: Meanwhile, whisk confectioners’ sugar, lemon juice, and buttermilk until smooth. Gently spread glaze over warm cake and sprinkle evenly with reserved sugar mixture. Cool completely, at least 2 hours. I poked small holes in my cake with a fork. You don’t have to…I just wanted some of the glaze to penetrate…