Preheat the oven to 400F and prepare the muffin tins by either lining 12-14 cups with paper liners or greasing them well.

Melt the butter in a microwave safe bowl, and set it aside to cool. Place the eggs and buttermilk out to slightly come to room temperature. You don’t want them to sit out for long, just long enough to take the refrigerator chill off.

Sift the glour, cocoa powder, baking powder and soda, and salt together. Stir in the sugar, then create a well in the center of the dry ingredients.

Stir together the melted butter, eggs, buttermilk, and vanilla extract until they are well mixed. Pour the wet ingredients into the well in the dry, and fold them together until the ingredients are combined. Fold in the berries and chocolate chips, then scoop the batter into the prepared muffin tins.

Bake for 18-20 minutes, or until a toothpick inserted the center comes out clean or with just a few moist crumbs.