Butter, for coating pan

TOPPING:

1/3 cup flour
¼ cup sugar
2 tbs dark brown sugar
½ tsp cinnamon
¼ cup (½ stick) cold unsalted butter

CAKE:

1 cup flour
1 tsp baking powder
½ tsp ground ginger
¼ tsp salt
¼ cup (½ stick) unsalted butter, softened
½ cup sugar
1 large egg
1 tsp vanilla
1/3 cup milk
1 ½ cups frozen blackberries (from one 10 oz pkg)

Preheat the oven to 350 degrees. Butter an 8” square pan; set aside.

For the topping: in a large bowl, stir together the flour, sugars, and cinnamon. Using a pastry cutter or your fingers, cut in the butter until the mixture resembles coarse crumbs. Refrigerate until ready to use.

For the cake: in a medium bowl, whisk together the flour, baking powder, ginger, and salt. In a large mixing bowl, cream the butter with an electric mixer on medium speed. Add the sugar; beat until light and fluffy. Beat in the egg and vanilla. Alternately beat in the flour mixture and milk until just combined.

Spread the batter evenly in the prepared pan. Scatter the blackberries over the batter. Sprinkle with the streusel topping. Bake for 45-60 minutes or until a toothpick inserted in the center comes out clean. Transfer to a wire rack to cool slightly before serving.