Adaption of a Recipe by John Barricelli that aired on an episode of the Today Show on March 6th, 2010. I did make some changes to the given recipe.
Great served warm with whipped topping.
For the streusel topping:
1 cup all-purpose flour
1 cup light brown sugar
1 teaspoon coarse salt
1/2 teaspoon ground cinnamon
1/2 cup (1 stick) cold unsalted butter, cut into small cubes
For the blackberry buckle:
1 1/4 cups all-purpose flour
2 teaspoons baking powder
1 cup (2 sticks) unsalted butter, at room temperature
1 cup granulated sugar
1/2 teaspoon coarse salt
4 large eggs
2 teaspoons pure vanilla extract
4 cups either blackberries, raspberries or blueberries
Confectioners' sugar (optional)
To make the streusel:
In a medium bowl, use a fork to stir together the flour, brown sugar, salt and cinnamon. Add the butter and, using your fingertips, quickly work it into the dry ingredients until pea-size crumbs form; set aside in the refrigerator.
To make the blackberry buckle:
In a medium bowl, whisk together the flour and baking powder; set aside. Set the oven rack in the middle position. Preheat the oven to 350 degrees F. Butter a 9-by-13-inch baking dish; set aside.
In a large bowl beat the butter, sugar and salt on medium-high speed until light and fluffy, 2 to 3 minutes. Beat in the eggs one at a time, and then the vanilla. On low speed, beat in the dry ingredients just until absorbed. Fold in the berries. Transfer to the prepared baking dish. Sprinkle the streusel over the top.
Bake until a cake tester inserted into the thickest part of the buckle comes out clean and the topping is nicely browned and crisp approximately 45 minutes. Transfer to a wire rack to cool for 10 minutes. Dust with confectioners’ sugar if you like and cut into squares.