Lemon Buttermilk Sheet Cake

Cake:
2 1/2 cups cake flour (no substitutions)
1 tsp. baking powder
1/2 tsp. baking soda
1/2 tsp. salt
3/4 cup buttermilk
3 Tbl. grated lemon zest
1/4 cup freshly squeezed lemon juice
1 tsp. vanilla extract
1 3/4 cups sugar
12 Tbl. (1 1/2 sticks) unsalted, softened butter (I have used salted butter)
3 large eggs plus 1 large egg  yolk

Glaze:
3 cups powdered sugar
3 Tbl. lemon juice
2 Tbl. buttermilk

Heat oven to 325 degrees.  Grease and flour 9x13 baking dish.  (You can also make it in a cookie sheet - sheet cake style.)

Whisk flour, powder, soda and salt in medium bowl.  Set aside.  In a measuring cup, combine buttermilk, lemon juice and vanilla.  Set aside.

In a stand mixer fitted with the paddle attachment, beat sugar and lemon zest on medium speed until moist and fragrant (about 1 minute).  Remove 1/4 cup of sugar mixture, cover and set aside.

Add softened butter to remaining sugar mixture and beat until light and fluffy (about 2 minutes).  Beat in the eggs and yolk, one at a time, until incorporated.  Reduce speed to low.  Add the flour mixture in 3 additions, alternating with the buttermilk mixture in 2 additions.  Mix until smooth (about 30 more seconds).

Scrape batter into prepared pan and smooth the top.  Bake until golden brown and toothpick inserted in center comes out clean (about 25-35 minutes).  Be careful not to overbake.  Cool cake for 10 minutes.

While the cake is cooling, whisk the glaze ingredients together until smooth.  Gently spread glaze over the cake and sprinkle with reserved sugar and lemon zest mixture.  Allow to cool completely, at least 2 hours.

This recipe is from America's Test Kitchen and it has become one of my favorites.  It sounds harder to make than it is.  If you zest the lemons and squeeze the juice, you can freeze them until you are ready to make the cake.  If you like lemon, I think you'll love this cake!!