01 - Set oven temperature to 400°F and line a baking sheet with parchment paper.
02 - Whisk together all-purpose flour, whole wheat flour, sugar, baking soda, and salt in a large bowl.
03 - Stir in dried cranberries and chopped walnuts, ensuring even distribution and coating with flour.
04 - In a separate bowl, whisk buttermilk, melted butter, and egg until combined.
05 - Pour wet mixture into dry ingredients and gently mix with a wooden spoon or hands until a shaggy dough forms; avoid overmixing.
06 - Turn dough onto a lightly floured surface and shape into a round loaf approximately 7 inches in diameter.
07 - Place loaf on baking sheet, cut a deep X across the top with a sharp knife, and brush with additional buttermilk.
08 - Bake for 35 to 40 minutes until golden brown and a skewer inserted in the center comes out clean.
09 - Transfer to a wire rack and cool for at least 30 minutes before slicing.