Preheat oven to 350°F.
FRUIT FILLING: Stir sugar and corn starch together in a large saucepan. Add berries, water and almond extract, stirring until thickened over medium-high heat, about 5 to 8 minutes. Remove from heat and pour into a 13 x 9-inch baking dish; set aside to cool.
TOPPING: Whisk together flour, sugar, baking powder, salt and lemon peel in a medium bowl. Cut butter into flour mixture using a pastry blender or two forks. Stir in milk to form a thick, doughy batter.
Drop spoonfuls of batter evenly onto surface of blueberry filling. Bake for 40 to 45 minutes or until topping is puffed and deep golden brown. Remove from oven and cool 15 to 20 minutes before serving.
TIP: To garnish, sprinkle coarse sugar over the batter just before baking.