Preheat an oven to 180 degrees C. Grease and flour a 23cm square baking dish. Whisk 1 cup flour, the baking powder and salt together in a mixing bowl.
Beat the copha and 1/2 cup sugar with an electric mixer in a large bowl until light and fluffy. Beat in the egg. Pour in the flour mixture alternately with the milk, mixing until just incorporated. Pour the batter into prepared pan then sprinkle evenly with blueberries.
Combine 1/2 cup sugar, 1/3 cup flour, cinnamon and butter in a bowl with a fork until crumbly and evenly mixed. Sprinkle evenly over the blueberries.
Bake in the preheated oven until a toothpick inserted comes out clean, about 35 minutes. Allow to cool before serving warm.