Preheat the oven to 350°F. Grease an 8½ × 4½-inch loaf pan or line it with parchment paper.
In a medium bowl, whisk together flour, baking powder, and salt. Set aside.
Zest the orange directly into the granulated sugar and stir to distribute the zest and fragrant oils.
In a large mixing bowl, use a rubber spatula to combine softened butter and cream cheese until smooth. Stir in the orange-infused sugar.
Add eggs one at a time, stirring until incorporated. Mix in vanilla extract.
Alternate adding the dry ingredients and buttermilk, beginning and ending with the flour mixture. Stir gently until smooth and just combined.
Spread half of the batter into the prepared pan. Sprinkle with half of the chopped cranberries.
Add the remaining batter and sprinkle with the rest of the cranberries. Gently swirl the berries into the batter, making sure exposed pieces are covered.
Bake for approximately 60–70 minutes, beginning to check around 55 minutes. The loaf is ready when the center is set and a cake tester comes out without wet batter.
Cool in the pan for 15 minutes, then transfer to a wire rack.
To make the glaze, whisk powdered sugar with the juice of half an orange. Add more juice as needed until smooth and pourable. Drizzle over the completely cooled loaf.