Coconut is an unexpected, but tasty addition the topping. You'll find yourself making this recipe a lot!
Combine 1/3 cup flour, 1/4 cup butter, coconut, brown sugar and cinnamon in medium bowl. Mix until moist and crumbly. Set topping aside.
Preheat oven to 357°F. Butter and flour 13x9x2-inch baking pan. Sift remaining 2 cups flour, baking powder and salt into small bowl. Using an electric mixer, beat remaining 1/2 cup butter in large bowl until fluffy. Gradually add 1 cup sugar, beating until well blended. Add eggs 1 at a time, beating to blend after each addition. Mix dry ingredients into batter alternately with milk in 3 additions each. Fold in blueberries. Transfer cake batter to prepared baking pan. Sprinkle topping evenly over batter.
Bake cake until tester inserted into the center comes out clean and topping is golden brown, about 40 minutes. Cool cake slightly. Serve warm or at room temperature.