Preheat oven to 350 degrees F. Grease or butter muffin pan.
In a large bowl, mix all-purpose flour, whole wheat flour, cocoa powder, sugar, baking powder, orange zest and salt.
In a separate bowl, combine milk, melted butter and egg. Add wet ingredients to dry ingredients and mix until just blended.
Fold in dried cranberries and chocolate chips.
Divide batter among muffin cups. Sprinkle with decorative icing sugar if desired.
Bake at 350 degrees F for 16-19 minutes, until a toothpick pulls clean from the center.
