Preheat the oven to 450°F. Spray a 12 cup muffin tin with cooking spray. Set aside.
If using fresh potatoes: Shred the unpeeled potatoes into a medium size mixing bowl using a box grater or food processor. Blot gently with a paper towel to remove any excess moisture. Don't rinse. If using frozen shredded hash browns: Thaw completely before adding to the mixing bowl.
Mix shredded potatoes, egg whites, Parmesan cheese, salt, onion powder, garlic powder and pepper together.
Scoop ¼ cup of potato mixture into each muffin cup. Usie a small glass to press the potato mixture firmly into the bottom and up the sides of each cup.
Spritz each nest with butter flavored cooking spray. Alternately, drizzle each with melted butter.
Bake for 22-25 minutes or until cooked through and golden. Sprinkle with shredded cheese in the last few minutes of baking.
Remove from the oven and gently run a knife or an offset spatula around each nest to loosen the edges. Allow to cool in the pan for around 2 minutes before attempting to remove.
To assemble: Top with sour cream and crumbled bacon. Garnish with finely chopped parsley or chives. Serve warm.