Preheat oven to 350°F.
In a medium bowl, combine the flour, baking powder and salt. Set aside.
In the bowl of an electric mixer, cream together the butter and sugar using the paddle attachment. Mix on medium low speed for two minutes until light and fluffy. Stop mixer at least once to scrape the sides of the bowl with a rubber spatula. Be sure there are no clumps of unmixed butter.
Add the lemon zest and combine.
Add the eggs one at a time, mixing after each addition.
Add the sour cream, lemon juice and vanilla. Mix until combined. (Mixture may separate a bit, but it will come together when flour is added)
Slowly add the flour mixture and mix until just combined. Stop the mixer, scrape the sides and bottom of bowl with a rubber spatula. Mix on low speed for an additional one minute.
Grease loaf pans generously with nonstick spray, or line pans with parchment paper. Spoon batter into pans, filling two-thirds full.
Bake for 45-60 minutes, or until center is done - an inserted toothpick or cake tester comes out clean. Mini loaf sizes will need less bake time (closer to 45 minutes). Full size loaves will need more bake time (closer to 60 minutes). All ovens bake differently so be sure to keep an eye on it. If the tops are browning too much, loosely cover them with aluminum foil and bake until centers are done.
Let bread cool in the pans for 10 minutes before removing to cool completely on a wire rack.
Prepare the glaze by combining the powdered sugar, milk and lemon zest in a small bowl. Add just enough milk to get a thick consistency.
Drizzle the lemon icing over the loaves after they have completely cooled. Sprinkle coconut shavings on top before icing sets. The icing should set within 20 minutes. Slice, serve and enjoy!