01 - Preheat the oven to 375°F. Line a 12-cup muffin tin with paper liners or lightly grease each cup.
02 - In a large bowl, whisk together the flour, sugar, baking powder, baking soda, and salt until evenly blended.
03 - In a separate bowl, beat the eggs then whisk in the vegetable oil, buttermilk, orange zest, orange juice, and vanilla extract until smooth.
04 - Pour the wet mixture into the dry ingredients and gently fold with a spatula just until combined; avoid overmixing.
05 - Fold the cranberries evenly into the batter.
06 - Divide the batter evenly among the prepared muffin cups and sprinkle the tops with coarse sugar if desired.
07 - Bake for 18 to 22 minutes, or until a toothpick inserted into the center comes out clean.
08 - Allow muffins to cool in the tin for 5 minutes before transferring to a wire rack to cool completely.