Preheat the oven to 180C/360F/Gas 4. Grease and line six 7.5cm/2in x 10cm/3in spring-sided cake tins with baking parchment.
For the cake, place the butter and sugar into a bowl and beat together until pale and fluffy.
Add the eggs, one at a time, beating well to combine before adding the next.
Add the flour and mix well.
Divide the cake batter among the six cake tins and place into the oven to bake for 25-30 minutes. Test by pushing a metal skewer into the centre of the cake; if it comes out clean the cakes are ready.
Remove from the oven and when cool enough to handle, remove from the tins and leave to cool on a wire rack.
For the filling, place the butter, vanilla seeds and sugar into a clean bowl and beat together until thick.
To serve, spread the raspberry jam onto three of the cakes. Top the jam layer with raspberries, then then add a dollop of buttercream topping to each.
Place one of the remaining cakes on top of each of the layered cakes and dust generously with icing sugar.