Preheat the oven to 180˚C/160˚C fan/gas mark 4. Line two standard 12-cup muffin tins with paper liners.
In a large bowl, combine the cocoa powder, flour, sugar, bicarbonate of soda, baking powder and salt.
Add the eggs, warm water, oil and vanilla to the dry ingredients. Stir to combine until the batter is smooth.
Fill the prepared muffin cups to two-thirds full. Bake for 20 minutes or until the tops of the cupcakes spring back when touched. Cool on a wire rack.
In a large bowl, beat the butter and icing sugar for one minute until well combined. Mix in the vanilla.
Add the melted, cooled chocolate and beat until combined, then beat in the Chocolate spread. Pipe the icing onto the cooled cupcakes and enjoy!