CAKES: Blueberry Crumb Cake

My neighbor made this for me and it's delicious! Next time I'm going to add the cheese filling from the German Streusel Cake (in my recipes). This is the recipe she gave me:

Cake:

6 Tbsp. (3/4 stick) unsalted butter
3/4 cup packed light brown sugar
1 tsp. vanilla extract
2 tsp. finely grated lemon zest (if you use the cheese filling omit the lemon from the cake)
2 large eggs
1 1/4 cups flour
1 tsp. baking powder
1/2 cup low-fat buttermilk

Topping:

3 cups frozen or fresh blueberries
4 Tbsp. (1/2 stick) unsalted butter, melted
1/3 cup packed light brown sugar
3/4 cup flour
1/2 tsp. ground cinnamon
1/2 tsp. baking powder

Set rack in middle level of oven and preheat to 350 degrees F. Mist a 10-inch round pan (2 inches deep) with cooking spray and line bottom with a disk of parchment paper. (I sprayed a 10-inch springform pan with PAM for baking w/flour and omitted the parchment).

For cake batter, combine butter and brown sugar in bowl with electric mixer on medium speed until light and creamy, about 2 minutes. Beat in vanilla and lemon zest, then add eggs, one at a time, beating until smooth after each addition.

Quickly stir flour and baking powder together; decrease speed to low and beat half the flour mixture into the butter mixture. Beat in buttermilk until absorbed, stop mixer and use a large rubber spatula to scrape down bowl and beaters. Beat in remaining flour mixture and use spatula to give batter a final mixing.

Scrape batter into prepared pan and spread out evenly. Top with blueberries, gently pressing them in.

For the crumb topping, mix butter and brown sugar in a bowl. Quickly combine flour, cinnamon and baking powder, and stir them into the butter mixture with a rubber spatula. Use your fingertips to break up the mixture into small crumbs; scatter crumb topping evenly over the blueberries.

Bake cake for about 55 minutes, or until well risen and golden and a toothpick inserted in center comes out clean. Cool in pan on rack for 5 minutes; invert cake onto a large plate and remove pan and paper.

Re-invert onto rack to cool completely. If you're using a springform pan, you just need to take the ring off and let the cake cool -- much easier than inverting the cake!