Preheat the oven to 375°F. Grease and line a 9x5-inch loaf pan with parchment paper.
In a medium bowl, whisk the flour, baking powder, baking soda, salt, and cinnamon.
2 cups all-purpose flour, 1 ½ teaspoons baking powder, ½ teaspoon baking soda, ½ teaspoon salt, ½ teaspoon ground cinnamon
In a large bowl, whisk the sour cream, milk, oil, eggs, sugar, vanilla, and orange zest until smooth.
½ cup sour cream, ¼ cup milk, ½ cup canola oil, 2 large eggs, 1 cup granulated sugar, 1 teaspoon vanilla extract, 1 teaspoon orange zest
Add the dry ingredients to the wet ingredients and stir gently until just combined and no dry pockets remain.
Fold in the cranberries and walnuts. Spoon the batter into the prepared pan.
1 ½ cups fresh cranberries, ½ cup chopped walnuts
Bake at 375°F for 10 minutes, then reduce to 350°F for 50–60 minutes or until a toothpick inserted in the center comes out clean.