Preheat oven to 350°F (180°C). Spray a Nordic Ware Alpine Forest Loaf Pan (see Notes) with baking spray with flour, using a pastry brush to ensure an even coating.
In the bowl of a stand mixer, whisk together granulated sugar and orange zest by hand until fragrant. Add butter; using the paddle attachment, beat at medium speed until light and fluffy, 3 to 4 minutes, stopping to scrape sides of bowl. Add eggs, one at a time, beating until combined after each addition and stopping to scrape sides of bowl. Beat in vanilla.
In a medium bowl, whisk together 1 2/3 cups (208 grams) flour, baking powder, and salt. With mixer on low speed, add flour mixture to butter mixture alternately with buttermilk, beginning and ending with flour mixture, beating until just combined after each addition.
In a small bowl, stir together cranberries and remaining 1 tablespoon (8 grams) flour; fold cranberry mixture into batter. Spoon batter into prepared pan. Firmly tap pan on a kitchen towel-lined counter several times to settle batter.
Bake until a wooden pick inserted in center comes out with a few moist crumbs, 55 minutes to 1 hour and 5 minutes. Let cool in pan on a wire rack for 10 minutes. Remove from pan, and let cool completely on a wire rack.
Garnish with confectioners’ sugar and sugared cranberries (see Notes) just before serving, if desired. Store in an airtight container for up to 3 days.