For the bread
1 Tbs. unsalted butter, softened
9 oz. (2 cups) unbleached all-purpose flour, plus more for the pan
3/4 cup granulated sugar
1 Tbs. baking powder
3/4 tsp. table salt
1-1/4 cups fresh or thawed frozen cranberries, halved if large
1 cup buttermilk
2 large eggs, at room temperature
1 tsp. pure vanilla extract
1-1/2 Tbs. finely grated fresh orange
4 oz. (1/2 cup) unsalted butter, melted and cooled
For the glaze
4 oz. (1 cup) confectioners’ sugar, sifted if lumpy
4 tsp. orange juice; more as needed
Make the bread
Position a rack in the lower third of the oven and heat the oven to 350°F. Butter and then flour the bottom and sides of a 6-cup (8-1/2 x 4-1/2-inch or 9 x 5-inch) loaf pan, tapping out any excess flour.
In a large bowl, combine the flour, sugar, baking powder, and salt. Whisk until well blended. Stir in the cranberries.
In a medium bowl, combine the buttermilk, eggs, vanilla, and orange zest. Whisk until blended. Pour the wet ingredients over the dry ingredients. Add the melted butter. Using a silicone spatula, gently fold until blended.
Scrape the batter into the prepared pan and spread evenly.
Bake, rotating halfway through, until the top is golden and a wooden skewer or toothpick inserted in the center comes out clean, 50 to 55 minutes.
Let cool in the pan on a rack for 30 minutes. Invert the bread and remove the pan, turn the bread right side up, and let cool completely.
Glaze the bread
In a small bowl, stir the confectioners’ sugar and the orange juice until smooth, adding more juice, 1 tsp. at a time, until the glaze is just pourable. Drizzle the bread with the glaze and let it set for 30 minutes. Store, covered, at room temperature for up to 2 days.