Preheat oven to 375F. Line a baking sheet with parchment paper.
In a medium-sized bowl, whisk together egg whites, sugar, cayenne, cinnamon and salt. Add the pumpkin seeds and toss to coat.
Spread seeds in a single layer across the parchment-lined baking sheet and bake for about 15 minutes. Stir them up a bit and pop them back into the oven until golden in color, about 5 minutes more. Taste and season with more salt if needed.