Preheat oven to 350 degrees.
In a large mixing bowl, mix together the flour, brown sugar, white sugar, salt, cinnamon, and baking powder.
Stir in the melted butter, milk, egg, vanilla extract until evenly combined. Gently stir in the blueberries.
Grease or line a 9x9 baking pan with parchment paper. Pour in the mixture and bake for 40 minutes, or until a toothpick inserted comes out clean.
Make the icing and drizzle on top. (Click the link above for the recipe.)