01 - Preheat oven to 350°F. Grease and line a 9x5-inch loaf pan with parchment paper.
02 - In a medium bowl, whisk together flour, baking powder, baking soda, and salt. Set aside.
03 - In a large bowl, beat softened butter and granulated sugar with an electric mixer until light and fluffy, approximately 2 to 3 minutes.
04 - Beat in eggs one at a time, mixing thoroughly after each addition until fully incorporated.
05 - Add lemon zest, lemon juice, and vanilla extract to the mixture. Blend until combined.
06 - Add half of the dry ingredients to the wet mixture and mix on low speed. Pour in milk, then add remaining dry ingredients. Mix until just combined; avoid overmixing.
07 - Pour batter into prepared loaf pan and smooth the top surface evenly.
08 - Bake for 45 to 50 minutes, or until a toothpick inserted into the center emerges clean. If the top browns excessively, loosely cover with aluminum foil.
09 - Let the cake cool in the pan for 10 minutes. Transfer to a wire rack and cool completely.
10 - Whisk together powdered sugar and lemon juice until the mixture reaches a smooth, pourable consistency.
11 - Drizzle icing over the cooled loaf. Allow icing to set before slicing and serving.