Preheat the oven to 350 degrees. Grease and line a 5x9 loaf pan with parchment paper.
Using a hand or stand mixer, combine the softened butter and sugar until creamy.
Add the eggs, then the lemon juice and zest to the bowl and continue mixing until they are both fully incorporated. Turn the speed up to high for about 30 seconds to a minute to add a bit of air to the mixture.
Slowly add the flour and baking powder to the wet ingredients, keeping the mixer at a slow speed until the flour is fully incorporated.
Pour the batter into the prepared pan and transfer to the oven to bake for approximately 1 hour. To check for doneness, gently press the center of the loaf to make sure that it feels baked through & doesn't feel jiggly or mushy.
Remove from the oven and pour the Lemony Glaze evenly over the top. Let cool for about 10 minutes before slicing.
For the Lemony Glaze:
Combine the powdered sugar and lemon juice in a small bowl. Mix well and work out the lumps. Add the zest and melted butter, stirring until combined well.