2 sticks unsalted butter, at room temperature, plus butter for greasing
2 1/2 cups all-purpose flour
1/2 tsp. baking powder
1/4 tsp. baking soda
1/4 tsp. salt
1 1/4 cups granulated sugar
3 eggs, at room temperature
1 cup buttermilk, at room temperature
1 1/2 cups sugar
1/4 teaspoon cream of tartar
1/8 teaspoon salt
1/3 cup water
2 egg whites
1 1/2 teaspoons pure vanilla extract
2 pints of
1 pint of blueberries
Preheat an oven to 325°F. Butter a half sheet pan and line it with parchment paper, set aside.In a medium bowl, whisk together flour, baking powder, baking soda and salt.
In another bowl, beat together butter and sugar using a handheld electric until smooth and pale. Add eggs one at a time, beating until the egg is incorporated fully. Add zest of lemons and buttermilk and beat until combined. Then add flour mixture and beat until flour is completely incorporated. But do not over beat it.
Pour batter into the prepared pan and spread evenly using a spatula.
Bake for 25 minutes or until golden brown, firm to the touch and toothpick comes out out clean. Let cake cool completely, about 1 hour. Run a knife along the sides of the pan. FROSTING: Place sugar, cream of tartar, salt, water and egg whites in a medium bowl. Beat with a handheld electric mixer for a few minutes. Place bowl on a small saucepan of boiling water beating constantly with the handheld mixer on high speed for 5-6 minutes. Remove from heat, add lemon zest and continue to beat with handheld mixer for 2-5 minutes until frosting has cooled down to almost room temperature.
Spread frosting on cooled cake. Then starting at the bottom, using the raspberries, create stripes horizontally leaving an inch in between rows. At ¾ of the way up shorten the rows to leave a 4x4 inch square space in the upper left hand corner of the cake. Cover the 4 x 4 in blueberries. Using a pastry piping bag with a star tip, fill in rows in between raspberry rows and pipe small stars on the blueberry square.
Because the frosting is meringue based, please leave cake inside a cool area until ready to cut and serve. If not, the frosting may deflate and melt in the heat and humidity.