Preheat oven to 350ºF/180ºC. Coat 2 x 12 cup muffin (large cupcake) pans with nonstick cooking spray or butter well.
Beat butter and sugar until light and fluffy. Add egg and vanilla and beat well to combine. Sift flour, baking soda and cornflour into butter mixture. Stir with a wooden spoon to mix well. The mixture will be thick. Take about 2 tablespoons of the mixture, roll into a ball and press into muffin pans and up the sides a bit. You should get about 16. Bake for 10-12 minutes. Remove from the oven and allow to cool for a few minutes. If they cups have puffed up, press down with the back of a teaspoon to form an indentation. Remove to a wire rack to cool.
Nutella Cheesecake filling
Beat all the ingredients together until well mixed and smooth.
To assemble cups take a small spoonful of Nutella and spread onto the base of the cups. Pipe or spoon filling in and top with a raspberry. Refrigerate until ready to serve. Prepare to be inundated!