Preheat oven to 350F degrees.
In a medium bowl combine biscuit mix and sugar.
Add sour cream, eggs, milk and vanilla extract.
Mix until combined. Batter will be very thick.
Gently stir in blueberries by hand.
Scoop batter into greased 9x13 baking dish and make sure it is evenly spread.
In a bowl, combine sugar, flour and butter.
Using your fingers or a pastry cutter, start combining mixture until it looks coarse and crumbly.
Sprinkle mixture over dough.
Bake about 30-35 minutes until a toothpick inserted comes out clean.
