Preheat oven to 180C. Line 18 large (185ml/ 3/4-cup) muffin pans with paper cases.
Use an electric beater to beat the butter, caster sugar and vanilla essence in a large bowl until very pale and creamy. Add the eggs 1 at a time, beating well after each addition, until combined. Use a large metal spoon to gently fold in half the flour alternately with half the milk, until well combined. Repeat with remaining flour and milk.
Spoon the mixture evenly into the paper cases. Bake in preheated oven for 20 minutes or until a skewer inserted into the centres comes out clean. Place on a wire rack to cool.
Meanwhile, combine raw caster sugar and water in a saucepan, and stir over medium-low heat until the sugar dissolves. Remove from heat and set aside for 20 minutes to cool to room temperature. Use an electric beater to beat the butter in a small bowl until white and creamy. Add the sugar syrup in a thin, steady stream and beat until well combined.
Use a sharp knife to cut a shallow V-shaped piece out of the top of each cake, about 1.5cm deep, leaving a 2cm-wide edge. Cut the piece of cake in half crossways to form 2 semicircles. Fill centre of each cake with 21/2 teaspoons of raspberry jam. Arrange 2 semicircles of cake in jam. Place mock cream into a clean piping bag fitted with a 1.5cm diameter fluted nozzle and pipe down centre between the "wings" on each cake.
