Heat oven to 350 degrees F (175 degrees C). Coat a Bundt pan well with cooking spray. OPTION-9 x 9 pan baked 350 for 40 mins.
Make the streusel topping: Mix 1 brown cup sugar, 2/3 cup flour, and cinnamon in a medium bowl. Cut in 1/2 cup butter or margarine; topping mixture will be crumbly. Set aside.
For the cake: Beat 1/2 cup butter or margarine in large bowl until creamy; add 1 cup white sugar, and beat until fluffy. Beat in egg and vanilla. Whisk together 2 cups flour, baking powder, and salt; add alternately with the milk to the creamed mixture, beating well after each addition.
Spread half the batter in the prepared pan. Cover with floured berries, top with 1/2 the streusel and add remaining batter by tablespoons. Cover with other 1/2 of streusel topping.
Bake at 350 degrees F (175 degrees C) for 55 to 60 minutes, until deep golden brown. Remove pan to wire rack to cool. Invert onto a plate after cake has cooled, and dust with confectioners' sugar. OPTION-Do not invert 9 x 9 pan dust with confectioners sugar and serve.