Preheat oven to 350 F. Grease a 8 by 8 pan and set aside.
In a bowl, mix together the streusel topping till crumbly and set aside.
In a bowl, whisk together the All Purpose Flour, sugar, baking powder, baking soda and salt.
In another bowl mix together buttermilk, melted butter and eggs.
Now mix the dry ingredients and wet ingredient together till just combined - do not overmix.
Transfer to the prepped baking pan and throw the blueberries on it.
Finally, sprinkle the streusel topping.
Bake for 40 minutes or till the topping turns golden brown on top. Cool completely before slicing and serving.