Preheat oven to 400 degrees F. arranging a rack in the center of the oven. Generously grease 12 muffin cups. Remove zest from the oranges. Mince the zest and measure out 1 tablespoon plus 1 teaspoon. Squeeze the juice from the oranges and reserve 2/3 cup.
In a medium bowl, toss together the cranberries, nuts and reserved orange zest. In a large bowl, combine the flour, baking powder and the 2/3 cup sugar and whisk together.
In a medium bowl, combine the reserved orange juice, melted butter and egg. Whisk until blended. Pour the liquid over the flour mixture and stir lightly 3 or 4 times with a rubber spatula, to combine. Add the cranberry-nut mixture and distribute evenly, using as few strokes as possible (the batter will not be perfectly smooth).
Quickly divide the batter among the prepared muffin cups. Sprinkle a pinch of the 1 teaspoon sugar over the top of each muffin. Bake 25 minutes in preheated oven or until golden. Let muffins rest in pan for about 2 minutes. Using a blunt knife, ease the muffins out onto a wire rack and let cool 15-20 minutes.