Preheat the oven to 160ºC / 320 °F
Grease and line a 8 inch/20cm square baking pan
Sift the flour and baking powder into a large bowl.
Add the eggs, butter ,caster sugar, vanilla extract and milk and beat until thoroughly mixed.
Pour into the lined baking pan
Bake for 25-30 minutes. To check if the cake is cooked insert a skewer and if it comes out clean the cake is ready.
Leave to cool in the tin for about 10 minutes and then move to a wire rack to cool completely. Place in the fridge before cutting through the cake to divide into 2 equal layers. Then using a square cookie cutter as a guide cut into 12 equal sized squares. I used a 6cm square cookie cutter.
Spread a layer of jam and buttercream on 6 of the cut squares and sandwich with the remaining 6.
Using a palette knife, apply the buttercream on the sandwiched cakes. Making sure that the corners are neat and smooth all around. Place in the fridge for about 20 minutes and then add another layer of buttercream making sure that it is smooth and neat. Place in the fridge for 20 minutes again to allow the buttercream to firm up making it easier when you are covering with the fondant.
Knead the fondant and roll out on a clean dry surface lightly dusted with powdered sugar or corn flour. Cover the individual cakes and using a fondant smoother to shape and push out any bumps around the top and the edges. Cut out excess fondant at the base of the cake to use as decorating as you prefer.