Preheat oven to 425°.
In a large bowl combine all filling ingredients. Toss to coat evenly and pour into a 2-quart baking dish. Tent with tin foil and bake 20-25 minutes.
Meanwhile, in a large bowl make the topping by combining flour, sugar, brown sugar, baking powder and salt. Blend in butter with your fingers, rolling the mixture between your palms until it has the consistency of coarse meal. Stir in just enough boiling water to combine.
Remove apples from the oven and spoon drop full of topping over them. Combine white sugar and cinnamon and sprinkle over the entire mixture. Bake until topping is golden, or about 30 minutes.