Preheat your oven to 350 °F. Grease a standard loaf pan ( 9x5x3 inches approximately) and set aside.
In a large mixing bowl, beat together the butter and sugar until creamy and smooth. Beat in the eggs, one at at a time until fully combined. Mix in the orange zest and juice until combined.
In a separate bowl, whisk together the flour, baking powder and salt. Add into the butter mixture and stir until mixed in well.
Spoon into the prepared loaf pan, smoothing out the top. Bake for 55-60 minutes or until a cake tester or toothpick inserted into the middle comes out clean. Remove from the oven and let cool until you can touch the pan safely. Turn out onto a rack to cool completely.
For the icing: Melt the butter in a small, glass bowl. Add the orange juice and zest. Whisk in the powdered sugar until smooth. You want the glaze to be a little thin so it will drizzle over the bread.