Using a mixer cream together the sugar and Stork until completely combined and very pale in colour. Add in the beaten egg and mix gently to combine.
Sieve the flour and baking powder into the mixing bowl and beat together until well combined.
Line two 25cm loose bottomed baking tins with grease-proof paper and spoon the cake mixture evenly between the tins.
Bake on the middle shelf of an oven at 150CFan for 40 minutes. After 40 mins insert a skewer into the centre of each sponge and it if comes out clean the sponge is baked, if not return to the oven until done.
Leave the sponge cake in the tin to cool for 5 minutes then remove from the tin and place on a wire rack to to cool completely.
To make the butter icing put the soft butter in a mixing bowl and beat with a whisk until very creamy and light in colour. Sift in the icing sugar and add the milk, gently beat together until very smooth.
Once the cake is cool spread one cake with a layer of raspberry jam and place this jam side up on a plate. Take the other sponge and spread over the butter icing before sandwiching together.
Finally, dust the top of the sponge with a light sprinkling of icing sugar to decorate and serve.
Always weigh out your eggs when making sponge cake.My Mum and I have tried using both butter and Stork margarine for baking sponge cake, however we found the Stork always gives you a lighter sponge so we only use that.My Mum also says that flours differ greatly between different countries. Michelle is Canadian and there are things that she can bake at home in Canada that turn out differently when she bakes them here in the UK.