Preheat the oven to 160°C fan / 180°C. Grease and line an 8" inch baking tin.
In a bowl, cream together the stork and caster sugar until light and pale.
Add in the eggs one at a time continuing to whisk.
If using frozen raspberries, toss in the flour before folding the flour into the mixture. If you are using fresh raspberries fold them in the next stage after the flour is added.
Fold in the white chocolate. Scoop the mixture into the baking tin and cook in the oven for 40-45 minutes.
Once baked, allow to cool slightly in the tin before moving to a wired rack to cool fully.
Melt the 20g of white chocolate and place in a piping bag. Snip off a the end and drizzle over the top of the cake.