Pre-heat oven to 180°C (160°C fan-forced). Lightly oil the base and sides of a 12-cup capacity muffin pan. Line the bases with baking paper if not non-stick.
For the cupcakes, place butter and sugar into the bowl of an electric mixer. Beat until pale and well combined. Add egg, mixing until well incorporated. Add the oil and mix well.
Reduce mixer speed and gradually add the combined flour, cocoa and bi-carb, alternating with the buttermilk until smooth. Add food colouring and vinegar, mixing until combined. Spoon batter evenly between prepared pans and cook for 18-20 minutes. Cool in pan for 10 minutes, before removing them to a wire rack to cool completely.
For the cream, beat cream cheese and sugar in the bowl of an electric mixer until smooth. Add cream and continue beating until thickened and smooth.
For assembly, cut each cake in half, pipe the cream onto the base and fill with raspberries. Replace lid and pipe some more cream on top finishing with a raspberry.