1. Make the cake: Preheat the oven to 350°. Grease a 2-quart nonstick Bundt pan with butter, then spray lightly with nonstick cooking spray.

2. In a small bowl, whisk the flour with the baking powder, salt and baking soda. In the bowl of an electric mixer fitted with the paddle attachment, cream the butter and sugar at medium-high speed until light and fluffy. Beat in the eggs, one at a time, until incorporated. Beat in the vanilla. Reduce the speed to low and mix in half of the flour mixture. Mix in the buttermilk, then the remaining flour mixture. Gently fold in the blackberries with a wooden spoon.

3. Pour the batter into the prepared Bundt pan. Bake until golden brown and a cake tester inserted in the center comes out clean, about 1 hour. Let the cake cool in the pan for 10 minutes, then invert onto a serving platter.

4. Make the orange glaze: In a small saucepan, whisk the orange juice with the sugar and simmer over low heat until the sugar dissolves.

5. Using a skewer or long, thin knife, prick deep holes all over the surface of the cake. Slowly spoon half of the glaze over the cake, letting it seep into the holes. Let the cake cool for 20 minutes longer. Spoon the remaining glaze over the cake and let set for 10 minutes. Slice and serve.