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

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

In a separate bowl, cream the softened butter and sugar together until light and fluffy.

Add the eggs one at a time, mixing well after each addition, followed by the vanilla extract.

Alternate adding the dry ingredient mixture and buttermilk to the butter mixture, starting and ending with the dry ingredients.

Gently fold in the fresh blackberries and dark chocolate chips into the batter.

Divide the batter evenly among the lined cupcake tins, filling each about two-thirds full.

Bake in the preheated oven for 18-20 minutes, or until a toothpick inserted comes out clean.

Allow the cupcakes to cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.