Blueberry Crumb Cake

Blueberry Crumb Cake
6 Tables unsalted butter                         ¾ cup lt. brown sugar, firmly pod.             1 teas vanilla
2 teas fine grated lemon zest                  1 ¼ cups flour                                         2 large eggs
1 teas baking powder ½ cup buttermilk
3 cups blueberries, rinsed/drained             4 Tables unsalted butter, melted
1/3 cup lt. brown sugar, firmly packed       ¾ cup flour
½ teas ground cinnamon                          ½ teas baking powder

Preheat oven to 350.
For the cake batter, combine the 6 Tables of butter and brown sugar, blend well, add in vanilla, lemon zest, eggs and beat until smooth. Combine the 1 ¼ cups of flour and 1 teas baking powder, using an electric mixer beat in half of this flour mixture, then add in the buttermilk, scraping the bowl often. Beat in the remaining flour mixture, scraping the bowl again. Turn the batter into a 10” round pan, 2” deep – sprayed with no stick spray and lined with parchment paper.
Top the batter with the 3 cups of blueberries, gently pressing them in. For the crumbs:
Combine butter and brown sugar; add in flour, cinnamon and baking powder by hand. Use your fingertips to combine all of these ingredients and then sprinkle evenly over the top.
Bake for 55 minutes. Cool in the pan for 5 minutes, then invert onto a rack and remove the parchment paper. Reinsert the cake onto a plate. Cool completely.