5 tablespoons unsalted butter, softened, plus more for pan
3/4 cup, plus 3 tablespoons sugar, plus more for dusting
1 cup all-purpose flour
1/4 teaspoon salt
1/4 teaspoon baking soda
3 tablespoons fresh lemon juice, plus finely grated zest of 2 lemons, plus more for garnish (optional)
1/4 cup milk
2 large eggs
Preheat oven to 350 degrees. Butter a 9-by-5-inch loaf pan. Dust with sugar, and tap out excess; set aside. Whisk together flour, salt, and baking soda. Stir together 1 tablespoon lemon juice and the milk.
Put butter and 3/4 cup sugar in the bowl of an electric mixer fitted with the paddle attachment. Mix until pale and fluffy, about 2 minutes. Mix in eggs and zest. Working in two batches, alternate mixing in flour mixture and milk mixture. Pour batter into prepared pan. Bake until a cake tester comes out clean, about 35 minutes.
Meanwhile, stir together remaining 3 tablespoons sugar and 2 tablespoons lemon juice. Upon removing cake from oven, immediately brush with lemon glaze. Let cake cool in pan 10 minutes. Unmold cake. Brush remaining glaze on top. Garnish with zest.