01 - Preheat oven to 350°F. Grease and flour a 9x5-inch loaf pan or line with parchment paper.
02 - Whisk together flour, sugar, baking powder, baking soda, and salt in a large bowl.
03 - In a separate bowl, whisk buttermilk, vegetable oil, eggs, vanilla extract, and orange zest if using.
04 - Pour wet mixture into dry ingredients and fold gently until just combined; avoid overmixing.
05 - Fold in dried cranberries and chopped walnuts carefully to distribute evenly.
06 - Transfer batter to prepared pan, smoothing the top evenly.
07 - Bake for 50 to 60 minutes or until a toothpick inserted in the center comes out clean.
08 - Allow the loaf to cool in the pan for 10 minutes, then move to a wire rack until completely cooled before slicing.