Preheat oven to 375°F. Lightly grease a 9-inch square pan with non-stick cooking spray. Set aside.
To prepare the streusel topping, combine the butter, brown sugar, flour, cinnamon, and nutmeg in a small bowl. Mix until it resembles course sand. Set aside.
In a medium bowl, combine the flour, baking powder, salt, and cinnamon. Set aside.
In a large bowl, cream together the butter, brown sugar, and white sugar. Beat in the egg, milk, and vanilla extract. Add the flour mixture and stir just until combined, being careful not to overmix. Gently fold in berries.
Spread batter into prepared pan. Sprinkle streusel over top.
Bake 50-55 minutes or until a toothpick inserted in middle comes out clean. Let cool in pan 10 minutes before serving.