Preheat oven to 180 C and grease and line a 20cm x 20cmm square cake tin with non-stick baking paper.

Place butter and chocolate in a medium-sized pan over a low heat and stir until melted and glossy.

Remove from heat and set aside for 10 minutes to cool.

Stir in sugar and eggs, then sift over the flour, baking powder and cocoa and stir until just combined.

Scrape into the pan, smooth the top, then sprinkle over the berries, pushing some down completely into the batter and leaving some poking out.

Bake for around 30-40 minutes, checking at the 30 minute mark – you want them fudgy and almost gooey, yet set. The edges should be firm.

Cool in tin then cut into squares.