A delicious blueberry muffin batter, baked into a cake and topped with an awesome streusel topping.
Preheat oven to 350 degrees. Cream together butter, sugar, egg and vanilla extract. In a separate bowl combine flour, baking powder and salt. In a separate bowl measure out milk. Add flour mixture and milk alternately until totally incorporated. Do not over mix. Gently stir in blueberries, being sure to have them evenly distributed. Pour into a 9" spring form pan that has been sprayed with non-stick spray.
In another bowl combine the streusel ingredients and cut them together. Be sure to not over mix into a paste. You want to be able to sprinkle the chunks of streusel over the top of the blueberry batter. Bake for 40-45 minutes or until golden brown. Remove from oven and let cool for at least 15 minutes. Run a knife around the edge of the pan and remove the outside of the spring form pan.
OPTIONAL: Glaze-Combine ingredients into a bowl and drizzle over the top of the cake. Serve warm or store at room temperature in an air tight container.