Preheat the oven to 350 degrees Fahrenheit. Grease a 9x5 loaf pan and line it with parchment paper with an overhang so you can easily lift the bread out when ready to glaze.
In a bowl, whisk together the flour, baking powder and salt. Set aside.
To zest the orange, using a vegetable peeler, peel the orange part of the peel only. You do not want the white pith part as is very bitter.
In a food processor (I use a mini food processor), process the orange peel and sugar until the peel is finely ground. This should be quick, about a minute. Set aside.
In the bowl of an electric mixer fitted with the paddle attachment, beat the butter and the orange sugar until light and fluffy, about 4-5 minutes, scraping down the sides of the bowl as needed.
With the mixer on medium-low, add the eggs one at a time, mixing well after each addition
With the mixer on low, add the flour mixture in thirds alternately with the buttermilk, starting and finishing with the flour mixture and scraping down the sides of the bowl to combine. Beat until just blended.
With a spatula, fold in the cranberries, then turn the batter into the prepared pan, smoothing out the top.
Bake on the center rack for 50-55 minutes, or until a toothpick inserted near the center comes out without wet batter clinging to it (moist crumbs are fine.) If the cake seems to be browning too quickly, loosely lay a sheet of foil over the top.
Remove from the oven and allow the bread to cool in the pan for about 10 minutes, then remove it, by lifting the bread using the parchment paper handles. Set the bread on a cooling rack and allow it to cool completely before glazing.
Meanwhile, make the glaze. The glaze should be quite thick and barely pourable. In a bowl, wish together the confectioner’s sugar with 2-3 tablespoons of the orange juice. Add additional orange juice until the desired consistency is reached.
Spread the glaze over the cooled bread.
Top with orange zest and sugared cranberries.