In a separate mixing bowl (or better yet, a food processor) combine the dry ingredients: flour, baking powder, brown sugar and salt. If you have a food processor, drop in the butter pieces and pulse the mixture until it's combined and the butter pieces are small and incorporated. Alternatively, you can use a pastry cutter or just 2 butter knives moving in opposite directions to cut and combine.
To finish the topping, in a separate mixing bowl, whisk together the milk and egg. Pour the egg mixture into the flour mixture and stir just until it turns into a sticky dough.
Drop portions of the dough on top of the berries so that it loosely covers most of the berry mixture. Remember, the dough will expand during baking. Cover it loosely with foil and bake it for 20 minutes. Remove the foil and bake it for another 25 minutes until the berries are bubbling and the topping is lightly browned.