• 2 cups all-purpose flour
• 2 teaspoons baking powder
• 1/2 teaspoon salt
• 1/2 cup butter (1 stick), at room temperature
• 1-1/2 cups sugar
• 1 teaspoon vanilla extract
• finely grated zest from 2 lemons
• 4 eggs plus 2 egg yolks
• 1 cup buttermilk
• For the glaze:
• juice from 2 Lemons
• 1/3 cup plus 1 tablespoon sugar
• 1 tablespoon light rum

1. Preheat oven to 325°F. Grease and flour a 13x9x2-inch baking pan. Sift together the flour, baking powder and salt, and set aside.
2. With an electric mixer, beat the butter at medium-high setting for 2 minutes. Add the sugar gradually, beating for 5 to 6 minutes. Add the vanilla extract and lemon zest and beat until incorporated. Add eggs and egg yolks, one at a time, beating well after each addition.
3. Turn mixer speed to low and add the sifted flour mixture alternately with the buttermilk. Scrape down sides of mixer bowl as needed, and beat until the batter is uniformly smooth. Pour batter into prepared pan, and bake for 50 minutes to 1 hour, or until a toothpick in center of cake comes out clean.
4. While the cake is baking, make the glaze:
5. Mix all ingredients and stir well several times until sugar is dissolved.
6. When the cake has baked and cooled for about 10 minutes, brush the surface with the glaze using a pastry brush. Use all the glaze.

From Grandma's cookbook Lemon sheet cake is not a particularly impressive-looking cake. After all, it's just your basic 9x13-inch cake. But this cake, in my humble opinion, is the best lemon cake you will ever eat. It's what I bake for myself and my family when we want something that's just plain good and doesn't require fanfare. Don't be tempted to skip the glaze (it needs no cooking and only takes a moment to stir together), because the glaze really completes the cake.