Preheat oven to 350° F. Line a standard muffin tin with liners, or spray with cooking spray.
In a large bowl add sugar and orange zest and stir well to combine. Add flour, salt, and baking powder and stir. Set aside.
In a separate medium bowl, combine the buttermilk, oil, eggs, orange juice, and vanilla.
Slowly add the wet ingredients to the dry ingredients, stirring just until combined. Fold in the halved cranberries.
Spoon the batter into prepared muffin pan and bake for 20-26 minutes. Makes 12 muffins.
While the muffins cook, make the orange glaze. In a small bowl, combine powdered sugar, orange juice, and orange zest. Whisk until smooth. Add more juice if needed to thin, or powdered sugar to thicken. Drizzle the glaze over the muffins.
Cranberry substitute: You could use dried cranberries, if you don't have fresh, or try substituting fresh or frozen raspberries or blueberries, for a fun flavor twist.Mini Muffins: For mini muffins, bake at 350°F (177°C) for about 11-13 minutes or until baked through. Use a toothpick to test for doneness.Freezing Instructions: Allow muffins to cool completely, then place in an airtight container of freezer bag for up to 3 months. Thaw at room temperature, or rewarm in the microwave for a few seconds.