Blueberry Streusel Coffee Cake

This is Carolee's contribution to our Mothers day:

Cake:
1/2 C butter, softened
1 3/4 C sugar
2 eggs
2 tsp. vanilla
3 1/2 C flour
2 tbsp. baking powder
1 tsp salt
1 1/2 C milk
3 C fresh or frozen blueberries
In mixing bowl cream butter and sugar.  Beat in eggs and vanilla.  Combine dry ingredients.  Add alternately with milk.  Fold in blueberries.  Pour into greased 9 x 13 inch pan.
For topping:
3/4 C sugar
1/2 tsp cinnamon
1/3 C cold butter
Combine sugar and cinnamon.  Cut in butter until mixture resembles course crumbs.  Sprinkle over batter.  Bake at 375 for 35-40 minutes or until a toothpick comes out clean.  Cool in pan on wire rack.