Preheat your oven to 350 degrees and grease a loaf pan- set aside.

In a medium bowl, stir together the flour, baking powder, and salt. Set aside. In a large bowl, beat together the butter, sugar, and lemon zest until light and fluffy. Add in the eggs, beating the batter between each egg addition. Add in about half of the flour mixture and beat until smooth. Then add in the lemon juice and stir. Add in the remaining flour and beat for several minutes until the batter is completely smooth.

Pour into your prepared pan. Optionally, if you want a crack in the cake down the middle, run a butter knife down the middle of the batter to just create a line. Bake for 45 minutes, or until the top is golden brown, and then cover gently with a foil tent and continue baking for an additional 20-25 minutes, or until a cake tester comes out clean. Cool completely in the pan, uncovered, and frost the cake when it's completely cooled.

In a medium bowl, whisk together the lemon juice and 2 cups of powdered sugar until smooth and well combined. If you'd like a thicker texture, add more powdered sugar until your icing is thick and drizzlable. Pour it over your cooled cake, and allow the icing to set before you slice and serve.