Beat 3/4 cup sugar and 1/2 cup butter until light and fluffy.
Add the egg and beat well.
Stir in dry ingredients together in a separate bowl.
Add flour mix and milk alternately and beat until smooth.
Spread in a greased 9x9 pan and top with blue with the blueberries.
Combine rest of ingredients and rub together with hands until crumbly.
Sprinkle over berries and bake at 350 degrees for 45 to 50 minutes.