Preheat oven to 350°, grease a bundt pan with baking spray. First, hydrate cranberries by mixing with orange juice in a glass measuring cup and heating in the microwave for 30 seconds. Set aside to cool.
Combine dry ingredients in a small bowl. In a separate bowl, beat egg whites with electric mixer to stiff peaks. In a third, large bowl, beat together sugar, oil and yolks until light yellow and fluffy. Stream in buttermilk, then the dry ingredients, then the cranberries in orange juice. Last, gently fold in egg whites.
Pour batter into prepared pan and bake 40- 45 minutes or until a toothpick inserted in center comes out clean. Cool completely then invert onto a large dinner plate. Make glaze by mixing powdered sugar, reserved buttermilk and orange peel until smooth, then spoon over cake.