Preheat the oven to 180°C/160° C fan/350°F/gas 4 and line a muffin tin with 12 purple paper cases.
In a large bowl, beat together the Stork, sugar, eggs, vanilla, self-raising flour, and milk until evenly combined, then fold through the blackberries. Divide the mixture between the cases and bake in the oven for 25 minutes until golden and springy to the touch. Transfer to a wire rack and allow to cool completely.
For the nests, crumble the Shredded Wheat into a bowl and pour over the melted milk chocolate. Stir well to combine and spoon the mixture on top of the cupcakes to form the nests. Softly whip the double cream and add a teaspoon to the centre of each nest. Top with the fresh blackberries and grated white chocolate to serve.