Cream butter; beat in sugar. Add eggs, one at a time, beating until smooth after each addition. Stir in sour cream. Stir in flour, baking soda, salt and vanilla; beat until smooth.
Fold in blueberries. Spread half the batter into a greased 9X13X2-inch baking pan. In bowl, mix brown sugar, nuts and cinnamon. Sprinkle mixture evenly over batter in pan. Spread on remaining batter.
Bake at 350 F or 175 C for 40-45 minutes.
Cool in pan. Cut in squares. Serve sprinkled with confectioners’ sugar.