Line a 9-by-5-inch loaf pan with baking or parchment paper. Preheat the oven to 180°C (350°F) / 160°C (320°F) fan-forced.

Sift together the flour, cocoa, baking soda, baking powder, and salt in a large mixing bowl. Stir in the sugars gently.

Microwave the butter in a large heatproof bowl for 20 seconds at a time, stirring in between. Whisk your vanilla and eggs into your butter until combined.

Make a well in the center of your dry ingredients, then add the wet ingredients and buttermilk. Fold the mixture gently with a spatula or wooden spoon until it is just combined - be careful not to overmix. To the batter, add 75 grams (1/2 cup) chocolate chips.

Pour mixture into prepared tin and top with an additional 35 grams (1/4 cup) chocolate chips. Bake for 45 minutes, or until a knife inserted into the center comes out clean. Allow to completely cool on a wire rack.