Preheat your oven to 350°F (175°C) and line a cupcake pan with paper liners.

In a large mixing bowl, whisk together the flour, cocoa powder, sugar, baking powder, baking soda, and salt.

In another bowl, cream the butter and sugar until light and fluffy, about 3-4 minutes.

Add the eggs and vanilla to the butter mixture, beating until smooth.

Gradually alternate adding the dry mixture and buttermilk to the egg mixture, mixing just until combined.

Gently fold in the blackberries and chocolate chips.

Scoop the batter into the lined cupcake pan, filling each liner about two-thirds full.

Bake for 18-20 minutes, checking for doneness with a toothpick.

Cool the cupcakes in the pan for 5 minutes, then transfer to a wire rack to cool completely.

Frost the cooled cupcakes with your preferred frosting.