Preheat oven to 170°C.
Place butter, chocolate, sugar, water, syrup and vanilla in a saucepan. Stir over medium heat with a wooden spoon for 5 minutes until chocolate melts. Set aside to cool.
Add eggs one at a time mixing well between each addition.
Whisk flours together and add to chocolate mixture and stir well.
Fill cupcake cases to half way and bake for 20 minutes. Check with a skewer to see if it comes out clean. If not cook for a further 5 minutes.