Place the butter and 100g of the white chocolate into a bowl over a bain-marie

Leave to melt, stirring occasionally

Set aside to cool while you carry on with the batter

Preheat the oven to 180º Celsius

Place the fructose and eggs into a large mixing bowl and whisk until at ribbon stage

Add the vanilla to the cooled chocolate and stir to combine *

Pour into the eggs and gently fold together until just combined

Sieve the flour and baking powder into the eggs and gently fold together until combined

Add the remaining chocolate and gently fold until well combined

Pour the batter into a greased, lined brownie tin, smoothing the top as best you can

Bake for 40 minutes then remove the tin from the oven

Leave to cool completely in the tin before turning out and slicing