Preheat oven to 425. Set a wire rack on top of a baking sheet. Spray rack with non-stick spray.
Grate sweet potatoes (I used a food processor) and squeeze all the moisture from them. I did this for a good 5 minutes – I find it makes them crisp up better in the oven.
Add sweet potatoes, egg whites, cheese, pepper, and rosemary in a large bowl and mix until combined. Scoop out 1 tablespoon of potato mixture (I used an ice-cream scooper) and set on wire rack. Press as thin as possible. Repeat until potatoes are gone.
Bake for 20-30 minutes, or until potatoes and dark around the edges and crispy.
Serve with smokey yogurt dip.
Smokey Yogurt Dip
Mix all ingredients together in a bowl. Serve as dipping sauce.