Prepare the Batter: Preheat your oven to 375°F (190°C) and line a muffin tin with paper liners or grease it. In a medium bowl, whisk together the flour, sugar, baking powder, baking soda, salt, and orange zest. In a separate bowl, combine the orange juice, buttermilk, melted butter, egg, and vanilla extract.

Mix Ingredients: Gradually fold the wet ingredients into the dry mixture until just combined. Be careful not to overmix; the batter should be slightly lumpy. Gently fold in the chopped cranberries.

Bake: Divide the batter evenly among the muffin cups, filling each about ¾ full. Sprinkle the tops with turbinado sugar if desired. Bake for 18-22 minutes, or until a toothpick inserted into the center comes out clean.

Cool: Let the muffins cool in the pan for 5 minutes, then transfer them to a wire rack to cool completely.