Prep the pan and oven: Heat the oven to 425°F (220°C). Line a 12-cup muffin tin with paper liners or grease well.
This high heat jump-starts the lift for tall muffin tops.
Mix the dry ingredients: In a large bowl, whisk together flour, sugar, baking powder, baking soda, and salt until well combined.
Combine the wet ingredients: In a medium bowl or large measuring cup, whisk eggs, oil, buttermilk, orange zest, orange juice, and vanilla until smooth.
Bring it together: Pour the wet mixture into the dry. Stir gently with a spatula until a few streaks of flour remain. Do not overmix.
Fold in cranberries: Add the cranberries and fold just until evenly distributed.
The batter should be thick and slightly lumpy.
Fill the cups: Divide the batter evenly among the 12 muffin cups, filling nearly to the top. Sprinkle with coarse sugar if you like a crunchy lid.
Bake high, then lower: Bake at 425°F for 5 minutes, then reduce the temperature to 350°F (175°C) without opening the door. Continue baking 14–16 minutes, until the tops are golden and a toothpick comes out with a few moist crumbs.
Cool and enjoy: Let the muffins rest in the pan for 5 minutes, then transfer to a wire rack to cool.
Serve warm or at room temperature.