Preheat the oven to 375°. Toss the blueberries with 2 teaspoons of the flour, 4 tablespoons of the sugar, the kirsch and the lemon zest. Pour the mixture into a 9-by-12-inch oval baking dish.
Mix the remaining 1 cup flour with 1 tablespoon of the sugar, the baking powder and salt. Cut in the butter until the mixture resembles coarse meal. Stir in 1/2 cup of the milk to make a very soft dough.
Drop the dough by spoonfuls on top of the berry mixture. Dampen your hands with half of the remaining milk and spread out the dough to cover most of the fruit. Brush the top of the dough with the rest of the milk. Sprinkle the surface with the remaining 2 teaspoons sugar.
Bake the cobbler for about 35 minutes, or until it is golden brown and the berries are bubbling. Serve warm with vanilla ice cream.