Preheat oven to 350°F (175°C). Grease a 9x5-inch loaf pan.
Mix Dry Ingredients: In a bowl, combine flour, baking powder, baking soda, and salt. Stir in orange zest and cranberries.
Cream Butter and Sugar: In another bowl, beat the butter and sugar until light and fluffy. Add the egg and mix well.
Combine Mixtures: Alternately add the flour mixture and orange juice to the butter mixture, starting and ending with the flour. Stir in nuts if using.
Bake: Pour the batter into the prepared loaf pan. Bake for 50-55 minutes, or until a toothpick inserted into the center comes out clean.
Cool and Glaze: Cool in the pan for 10 minutes, then remove to a wire rack to cool completely. Mix glaze ingredients and drizzle over the cooled bread.