Beat butter at medium speed with an electric mixer 2 minutes or until creamy. Gradually add 1/2 cup sugar, beating 2 to 3 minutes. Add eggs and next 3 ingredients, beating until smooth.
Combine flour, baking powder, and salt. Gradually add to butter mixture, beating until blended. Pour batter into a lightly greased 9-inch spring-form pan.
Combine blueberries and next 3 ingredients. Sprinkle over batter.
Bake at 350 degrees Fahrenheit for 35 to 40 minutes or until wooden pick inserted in center comes out clean. Cool in pan on a wire rack 10 to 15 minutes; remove from pan, and cool on wire rack 10 minutes.
Whisk together powdered sugar and milk until smooth. Drizzle over cake.