In a saucepan, off the heat, combine fruit, sugar and cornstarch. Bring to a boil and simmer for about 2 minutes or until sugar has melted. Pour into a 20-cm (8-inch) square pan or a 2-litre (8-cup) soufflé dish. Set aside.
With the rack in the middle position, preheat the oven to 190 °C (375 °F).
Dough
In a bowl, combine flour, sugar, baking powder and salt. Add shortening and combine with a pastry blender or your fingers until it is the size of peas.
Add milk and vanilla. With a wooden spoon, stir until flour is moistened, but texture is still lumpy. Spread dough over fruit with your hands. Sprinkle sugar over cobbler.
Place the baking dish on a baking sheet. This will contain overflowing juices.
Bake for about 50 minutes or until a toothpick inserted in the centre of the dough comes out clean. Let rest for 10 minutes before serving.