Preheat the oven to 375F. Spread your fruit into a deep-dish pie plate or similar-sized baking dish. In a small bowl, stir together the sugar and cornstarch and sprinkle overtop. Gently toss to combine.
Roll the pastry out about 1/8-inch thick and cut or tear into pieces an inch or two long and half as wide and scatter, haphazardly and overlapping, over the fruit. Brush with beaten egg or cream, and sprinkle with coarse sugar.
Bake for 45 minutes, or until the fruit is soft and bubbling and the topping is golden and crunchy. Serve warm, with ice cream. Serves 6.