Grease the ramekin. Brush a small microwave safe ramekin with butter, covering the base and sides.
Mix the dry ingredients. Add the maida, cocoa powder, baking powder and salt to the ramekin and mix well.
Add the wet ingredients. Pour in the milk, maple syrup and melted butter. Mix until the batter is smooth with no dry pockets.
Add the chocolate. Push the square of dark chocolate into the centre of the batter. Do not mix.
Microwave. Cook for 30 seconds, check, then continue in 10 second bursts. Stop when the top is set and the centre still wobbles slightly. This usually takes 35 to 45 seconds in total.