Preheat oven to 400 degrees F (200 degrees C). Line a 9X13 baking pan with aluminum foil.
In a food processor, mix the flour, 1/2 cup sugar, baking powder, salt and cinnamon. Add butter and pulse until the mixture resembles coarse crumbs. Stir in 1/3 cup boiling water just until mixture is evenly moist.
In a separate bowl, dissolve the cornstarch in cold water. Mix in remaining 3/4 cup sugar, lemon juice, and berries. Transfer to a skillet, and bring to a boil, stirring frequently. Spread berry mixture in the baking pan. Drop dough over the berries by spoonfuls. If desired, sprinkle cinnamon and sugar mixture over the dough.
Bake 25 minutes in the preheated oven, until dough is golden brown.