Preheat the oven to 375°F (190°C) and line the muffin tin with paper liners or spray with non-stick cooking spray.
In a large mixing bowl, whisk together the flour, sugar, baking powder, baking soda, and salt until combined.
In a separate bowl, mix the buttermilk, melted butter, eggs, and orange zest until well combined.
Pour the wet ingredients into the dry ingredients and gently fold using a spatula, being careful not to over-mix. The batter should be slightly lumpy.
Fold in the cranberries and chopped pecans until evenly distributed.
Divide the batter evenly among the muffin cups, filling each about ¾ full.
Bake in the preheated oven for 18-20 minutes or until a toothpick inserted into the center of a muffin comes out clean.
Allow muffins to cool in the tin for 5 minutes before transferring to a wire rack to cool completely.