Preheat oven to 450°. Stir together hash browns, egg whites, Parmesan cheese, onion powder, salt, garlic powder, and desired amount of freshly ground pepper. Press about 1/4 cup potato mixture into each cup of a lightly greased 12-cup muffin pan; coat with vegetable cooking spray. Bake 20 to 25 minutes or until golden. (Bake in a 24-cup miniature muffin pan 20 minutes, if desired.) Remove from oven, and cool in pan on a wire rack 5 minutes. Gently run a knife around nests to loosen edges; remove from pan to a serving platter. Top nests with colby-Jack cheese, sour cream, bacon, and chopped fresh chives.