Preheat oven to 350 degrees.
Grease a 8 x 8 inch pan.
Mix butter, sugar, egg, salt, flour, baking powder and milk in a large bowl.
Spread in the prepared pan.
Spread blueberries on top.
In a bowl mix the remaining sugar, cinnamon, flour and butter until crumbly.
Spread over blueberries.
Bake 30-40 minutes at 350 degrees.
Great served warm with ice cream.