Mix the dry ingredients

• Put the cocoa powder, protein powder, flour, sweetener, baking powder and salt in a mug.
• Stir with a spoon until evenly combined and no lumps remain.

Add the milk and chocolate centre

• Pour in the milk and stir until the batter is smooth and thick.
• Push the dark chocolate chunk into the middle of the batter so it is covered.

Microwave the mug cake

• Microwave on high until the top is set but the centre is still molten.
• Let it stand for a moment before eating.