Preheat your oven to 350°F (175°C).
In a large mixing bowl, combine the dry ingredients: flour, sugar, baking powder, baking soda, salt, and cinnamon. Stir until well mixed.
In a separate bowl, whisk together the wet ingredients: melted butter, eggs, buttermilk, and vanilla extract until smooth.
Pour the wet ingredients into the dry ingredients and mix gently until just combined.
Fold in the chopped cranberries and walnuts until evenly distributed.
Pour the batter into a greased 9x5-inch loaf pan and smooth the top.
Bake in the preheated oven for 55-60 minutes, checking for doneness with a toothpick.
Allow the bread to cool in the pan for 10 minutes before transferring to a wire rack to cool completely.