Preheat oven to 350 degrees F/ 180 degree C
Butter a rectangular loaf pan with parchment paper.
In a mixing bowl, whisk flour,baking powder and salt.
With a hand mixer, whisk the butter to cream like consistency. Add 1 cup of sugar and 4 eggs one by one. Add vanilla extract and lemon zest.
Slowly add the dry flour mixture and lemon juice on that mixture. Incorporate everything nicely.
Pour in the loaf pan and bake until 55 to 60 minutes or the tester inserted came clean. Time may vary in each oven.