Heat the oven to 180°C (160°C fan) 375F, gas 5.
Place 24 paper baking cups in the muffin pan.
Beat the egg with the oil, sugar, salt, cream cheese and buttermilk.
Mix the flour with the baking powder and baking soda.
Beat the egg mixture into the flour quickly, until all the ingredients are moist.
Spoon half the dough into the paper cups until half full.
Place 1-2 raspberries on each.
Spoon the remaining dough on top.
Bake on the middle shelf for 13-15 minutes. (Test with a wooden toothpick. If it comes out clean, the cupcakes are done.)
Cool on a wire rack.
Purée the raspberries with a hand-held mixer.
Press the purée through a sieve.
Mix the raspberry purée with the cream cheese and sugar until smooth and spoon into a piping bag with a star-shaped nozzle.
Squeeze the raspberry cream onto the cupcakes and sprinkle with sugar strands.