Preheat your oven to 180 °C/350 °F.
Grease two 20 cm/8 inch cake tins with butter or cooking spray, and line the bases with circles of greaseproof paper.
Add the softened butter and granulated sugar to a large mixing bowl. Use an electric whisk or stand mixer to cream the butter and sugar together until light and fluffy. This should take 5-10 minutes and the butter will be visibly lighter in colour.
Add the eggs to the mixture, one by one, beating well after each addition using the electric whisk.
Whisk in the vanilla extract.
Add the self-raising flour and baking powder to the bowl. Use a spatula or wooden spoon to GENTLY fold in the flour, being careful to avoid overmixing the batter.
Divide the cake batter between the two cake tins and use a spatula to evenly spread out the mixture.
Bake the tins in the middle shelf of the oven for 15-18 minutes until they are golden brown on top.
Allow the cakes to cool for a few minutes in their tins, then remove the cakes from the tins and peel off the greaseproof paper.
Leave the cakes to cool COMPLETELY whilst you prepare the buttercream. You can transfer the cakes to the fridge if you are in a pinch.
Prepare the buttercream: add the softened butter, vanilla extract and icing sugar to a large bowl. To avoid making a mess, first mix together the buttercream with a wooden spoon until the sugar is all incorporated. Then use an electric whisk or stand mixer to beat the buttercream for 3-5 minutes until it is pale and fluffy in texture.
Once the cakes have cooled, spread or pipe the buttercream onto the top of one cake layer. Top the buttercream with the raspberry jam then add the final sponge cake on top.
To serve, dust the cake with a little icing sugar. Enjoy!