Preheat oven to 350 degrees. Cream together the butter and granulated sugar for 8 minutes using a hand mixer or stand mixer. The result will be a light and fluffy mixture, light in color.
Add in the egg and lemon zest, beat for another minute to fully combine.
In a separate bowl, combine the flour, baking powder and salt. Stir to combine. Add in 1/3 of the flour mixture, beat until combined. Add in 1/2 of the milk, beat until combined. Add in another 1/3 of the flour, beat to combine. Add in the remaining milk plus the 1 Tbls lemon/lime juice, beat to combine. Add in the last of the flour and beat until fully combined. For each addition, beat for about one minute and scrap the bowl between additions. Batter should still be light and fluffy.
Scrap batter into loaf pan that has been sprayed with cooking spray. Bake for 20 minutes, rotate the pan 180 degrees for even cooking and bake for a remaining 20 minutes or until a toothpick inserted comes out clean.
Set cake in pan on wired rack and let cool for 20 minutes. Take out of pan and let cool on wire rack completely.
While cake is cooling, mix the remaining ingredients together (except for the additional powdered sugar for garnish). Pour evenly on top of cake. Serve with a light dusting of powdered sugar and enjoy!