In a large bowl, combine peaches, sugar, brown sugar, cinnamon nutmeg, lemon juice, and cornstarch. Toss to coat and pour into a 2 quart baking dish. Bake in preheated oven for 10 minutes.
Meanwhile, in a large bowl mix the topping: add the flour, sugar, brown sugar, baking powder, and salt. Blend in butter with a pastry blender until the mixture resembles coarse meal. Stir in boiling water until just combined.
Remove peaches from the oven and drop spoonfuls of the topping over them. Sprinkle with the 3T sugar and 1t cinnamon making sure to cover the entire pan with the cinnamon sugar mixture. Bake until topping is golden, about 30 minutes