Preheat your oven to 400.
Place the diced peaches in a bowl and sprinkle the sugar over them. Toss to coat.
Press the puff pastry squares into any muffin tin you prefer, and spoon the peaches into each cup. Brush the edges of the pastry with the egg wash. Bake for 15-20 minutes, until the pastries are cooked and golden brown.
Dust with powdered sugar and serve immediately!
Makes nine cups.
