Blueberry Coffeecake with Streusel Topping

2 c. flour
1 c. sugar
3 tsp. baking powder
1 tsp. salt
1/2 c. butter flavored Crisco
1 c. milk
1 egg
1 c. blueberries

Streusel Topping:
1/2 c. chopped walnuts
1/c. brown sugar
1/4 c. flour
1/2 tsp. cinnamon
3 tsp. butter or margarine

Glaze:
1 c. confectioner's sugar
2 Tb. milk
1/4 tsp. vanilla

Preheat oven to 350 degrees. Beat all ingredients except for blueberries, in a large bowl on low speed for 30 seconds, then beat on medium speed for 2 minutes, scraping bowl occasionally. Prepare streusel topping, mixing all ingredients until crumbly.
Grease or spray 13 x 9 x 9 " square pan. Spread 1/2 the batter in the pan. Sprinkle blueberries over batter then top with remaining batter. Sprinkle with streusel topping. Bake for 35-40 minutes. Mix glaze ingredients together and drizzle over cake.