blueberry coffee cake

i'm trying to do more baking on the weekends and was feeling like coffee cake this morning. which means no time for anything with dough that needs to rise. so after a little snooping on allrecipes.com, i combined a couple recipes to come up with this one. this recipe pretty forgiving and you could switch out a lot. for example, i used frozen blueberries, but i think you could swap in just about any other berry or even sliced peaches. and i used a combo of sour cream and milk to give the dough moisture, but you could just use 3/4 cup milk, or sour cream, or buttermilk (oooh, doesn't that sound fun?)... have at it! also, the original recipe called for this to be baked in a bundt pan, which i do not own, but a 9x13 works just fine. yay, improvising!
p.s. you will be excited when this comes out of the oven looking and smelling so yummy, but please let it cool a bit before chowing down - those blueberries are little heat bombs!

blueberry coffee cake
1/2 c. brown sugar
1/3 c. flour
1/2 t. cinnamon
1/4 c. butter

2 c. flour
2 t. baking powder
1/2 t. salt
1/2 c. butter
1 c. sugar
1 egg
1 t. vanilla
1/2 c. sour cream
1/4 c. milk
1 1/2 c. blueberries *(see below)

heat oven to 350. coat a 9x13" baking dish with cooking spray. make the streusel topping: mix brown sugar, 1/3 c. flour, and cinnamon in a medium bowl. Cut in 1/4 c. butter; topping mixture will be crumbly. set aside.
for the cake: beat 1/2 c. butter or margarine in large bowl until creamy; add 1 c. sugar, and beat until fluffy. beat in egg and vanilla. whisk together flour, baking powder, and salt; add alternately with the milk to the creamed mixture, beating well after each addition. gently fold in berries. spread the batter in the prepared pan. crumble streusel on top. bake for 40 minutes, until top is golden brown.

*(seasonal substitute: roughly chopped fresh cranberries & the zest of half an orange)