Preheat oven to 350 and spray a 13×9 pan with cooking spray.
Mix 2 cups flour, brown sugar and cinnamon together in a medium bowl. Add to food processor. Cut butter into one inch pieces and add to processor. Process until crumbly. Set aside.
Put 1/2 cup soft butter, sugar, eggs and vanilla in mixing bowl. Mix until well blended.
Mix together 4 cups flour and the baking powder. Add flour mixture and orange juice alternately to butter mixture until well combined.
Pour batter into greased 13/9 inch baking dish. Top with crumb mixture.
Bake for 55 minutes or until toothpick comes out clean.
Cool and cut into squares. Serve with ice cold orange juice!