1 cup (2 sticks) unsalted butter, softened, plus more for pan
3 cups all-purpose flour (spooned and leveled), plus more for pan
3/4 cup low-fat buttermilk
Zest of 2 lemons, finely grated
1/3 cup fresh lemon juice (about 2 lemons)
1 1/2 teaspoons salt
1/2 teaspoon baking powder
1/2 teaspoon baking soda
2 cups sugar
5 large eggs
2 cups confectioners' sugar
3 to 4 tablespoons fresh lemon juice
Place confectioners' sugar in a medium bowl or liquid measuring cup; stir in lemon juice (glaze should be thick, yet pourable).
Add more sugar or lemon juice, as necessary, to achieve desired consistency.
Preheat oven to 350 degrees, with rack in lowest position.
Butter and flour two 4 1/2-by-8-inch (6-cup) loaf pans.
In a small bowl (or liquid measuring cup), combine buttermilk with lemon zest and juice.
In a medium bowl, whisk together flour, salt, baking powder, and baking soda.
With an electric mixer, cream butter and sugar until light and fluffy.
Add eggs, one at a time, beating well after each addition.
With mixer on low, add flour mixture in three parts alternately with the buttermilk mixture in two, beginning and ending with flour; beat just until smooth (do not overmix).
Divide batter evenly between pans; smooth tops.
Bake until a toothpick inserted in centers comes out clean, 50 to 60 minutes (tent with foil if browning too quickly).
Cool 15 minutes in pan.
Turn out cakes onto a rack; cool completely before glazing.
Set rack with cakes over a baking sheet lined with waxed paper.
Pour glaze over cakes, letting it run down the sides; let dry, about 30 minutes.