Victoria sponge - single tin method

6.25 oz unsalted butter, very soft
6.25 oz SR flour
1 tsp baking powder
3 eggs, at room temperature, lightly beaten
6.25 oz golden caster sugar
1 tsp vanilla extract

For the filling
4-5tbsp raspberry jam
Castor sugar for dusting

Preheat the oven to 175C/gas mark 4.

1. Grease.a 1 x 20cm sandwich tin, line the base with disc of baking parchment and the sides with a 7cm-high collar of baking parchment as well, to allow for the rise. 
2. Sift the flour and baking powder into a bowl, then add the butter (in knobs), the eggs, sugar and vanilla. Beat together with electric mixer until thoroughly blended, taking care not to over-mix so you will have a light sponge. Scrape the batter into the tin or tins and level the top.  Bake for 30-35 minutes, until the cake springs back to the touch or a skewer inserted into the centre comes out clean.
3. Remove from the oven and leave for a couple of minutes, then run a knife around the rim to loosen the cake from the tin and turn out on to a wire rack. Peel off the paper and leave until completely cool.
4. Cut in half and sandwich together with raspberry jams and dust the top with castor sugar.