Preheat oven at 375. Coat 8x8 pan with cooking spray.
In a small bowl, gently toss peaches with brown sugar until sugar starts to dissolve; spoon fruit into prepared baking pan
In another small bowl, mix together flour, granulated sugar, cinnamon and salt; add eggwhites and combine with your fingers until mixture comes together and starts to crumble. Drop clumps of flour mixture over fruit; drizzle with melted butter
Bake until fruit just starts to bubble, about 45 minutes. Allow to cool slightly and serve warm.