Preheat oven to 375*F. Butter a round pie baking dish.
Pour the blueberry pie filling into the pie dish, add apples, sprinkle the cinnamon over the top, and mix to combine.
In a food processor combine the flour, sugar, salt, baking powder, and butter. Process until it resembles coarse meal.
Transfer to a large bowl, add the milk and the egg, and stir until the mixture is wet and sticky.
With a spoon distribute the dough over the bluberry and apple mixture, until they are completely covered.
Place a piece of aluminum foil on the rack directly under the pie dish to catch any juices that might spill from the dish. Check your cobbler after 30 minutes and see if the crust has already turned golden brown. If it is, cover it with a piece of aluminum foil to prevent it from over browning.
After an additional 30 minutes, take your cobbler out of the oven.
Let the cobbler cool for about 30 minutes before you serve it. Vanilla ice-cream or whipped cream are a nice complement to the warm cobbler. Sprinkle with some cinnamon over the top for an even more lifting taste experience.