Preheat oven to 375 degrees. Butter sides and bottom of a 9-inch spring form pan.
In a small bowl, toss berries with one tablespoon flour. Set aside.
In a medium bowl, whisk 2 cups flour, baking powder and salt. Set aside.
In a mixing bowl, beat the butter and sugar until fluffy. Beat in egg.
Add the flour mixture alternately with milk and vanilla.
Fold berries into batter and spread batter into prepared pan.
In a medium bowl, crumble topping ingredients together with hand to make crumbs. Sprinkle crumbs over batter.
Bake cake for 35-40 minutes, testing with a toothpick.
Allow to cool in pan for 15 minutes before loosening from pan