Preheat oven to 325 degrees. Line 12-well muffin tin with liners. In large bowl, whisk together sugar and oil. Add eggs, one at a time, whisking in between.
In a separate bowl, combine flour, baking powder, and salt. Add half the flour mixture to wet ingredients and whisk to combine. Add half the milk and stir, then add the remaining flour until incorporated. Finally, add the remaining milk, orange juice, and orange zest and stir just until combined.
Fold in cranberries. Transfer batter to muffin tin, filling wells ¾ full. Bake for 15-20 minutes or until toothpick come out clean when inserted into middle of muffins.
While muffins are baking, prepare glaze by whisking together powdered sugar and orange juice in small bowl. Once muffins are done, brush glaze on immediately and sprinkle with orange zest (optional). Let it sit for 10 minutes before taking out of pan and transferring to cooling rack.