Center a rack in the oven and preheat to 350 (F). Butter two 9 x 2 inch round cake pans and line the bottom of each pan with a round of buttered parchment or wax paper. Put the pans on a baking sheet.
In a medium bowl, whisk together 2 1/4 cups cake flour, 1 tablespoon baking powder, and 1/2 teaspoon salt. Set aside.
In another medium bowl, whisk together 1 1/4 cups milk and 4 egg whites. Set aside.
In the bowl of a stand mixer fitted with a paddle attachment, beat together 1 1/2 cups sugar and 2 teaspoons lemon zest on low speed, until the sugar is moist and fragrant. Add 1 stick of butter to the lemon and sugar mixture and beat at medium speed until the butter and sugar are very light and fluffy. Beat in 1/2 teaspoon of lemon extract, then add one third of the flour mixture, still beating on medium speed. Beat in half of the milk and egg mixture (from the third step), then beat in half of the remaining ingredients until incorporated. Add the rest of the milk and egg mixture, beating until the batter is homogenous, then add the last of the dry ingredients and continue beating until just incorporated.
Divide the batter between the two pans and smooth the tops with a rubber spatula. Bake 30 to 35 minutes, or until the cakes are well risen and springy to the touch. A toothpick inserted in the center of each cake round should come out clean.
Transfer the cakes to a cooling rack and cool for about 5 minutes, then run a knife around the sides of the cakes, unmold them, and peel off the paper liners. Invert and cool to room temperature right side up. While the cakes are still warm, poke both rounds all over with a fork. Make the lemon glaze by stirring together 1/4 cup sugar and 3 tablespoons lemon juice in a small bowl. Use a rubber spatula to divide glaze evenly and spread all over the tops of each cake round. When the cakes have cooled, frost each cake with Earl Grey tea frosting (recipe follows).