Preheat the oven to 180C fan/200C/400F/gas mark 6 and line an 8 inch baking tin.
Start by whisking the eggs on high speed with an electric mixer for 5 minutes, until pale and fluffy. Add the sugar and whisk again.
Add in the melted white chocolate, melted butter and vanilla extract and whisk until combined. Fold in the flour and butterscotch powder until totally combined.
Add the chopped chocolate and fold again. Pour into the lined tin and bake 30 minutes. Let cool before decorating with icing sugar/edible glitter. Slice and serve!