Preheat your oven to 180C / 160C fan / gas mark 4 / 350F. Grease and line a traybake pan (33 by 23cm / 13 by 9ins).

In a large bowl, beat together the butter and sugar thoroughly, until the mixture starts to look a little bit paler.

Add in one egg at a time and stir until each egg is completely mixed in before adding the next one.

Add in the vanilla extract and stir to ensure it is evenly mixed in.

Add in half the flour and stir gently until mixed in. Add in the remaining flour and, again, stir gently until the flour is mixed in.

Add in the 4 tablespoons of milk and stir until mixed in.

Tip the mixture into the lined traybake pan. Smooth over the surface with the back of your wooden spoon.

Put the traybake into your preheated oven for 35-40 minutes. After 35 minutes, remove from the oven and check to see if it’s done using a skewer inserted into the centre of the cake. If the skewer comes out clean, it is cooked. If the skewer is covered in batter, return to the oven for a further 3 minutes and test again. Repeat if necessary, until the skewer comes out clean. (See Note 1.)

Allow the cake to cool in the tin for 10 minutes, then turn it out onto a cooling rack (See Note 2.) and allow to cool completely. This should take approximately 1 hour.

Don’t try and decorate the traybake cake until it is completely cold!

Put the softened butter, vanilla extract and sieved icing sugar in a bowl and beat together until smooth.

Carefully cut the traybake cake in half through the middle (I find it easiest to do this with a bread knife) and remove the top of the cake. Try to ensure the cut surface is as level as possible.

Spread the jam evenly all over the cut surface.

Spread the buttercream evenly over the jam, then put the rest of the cake back on top. (Take care to ensure the top of the cake does not break when you do this!)

Finally, dust the top of the cake with icing sugar. (I just use a sieve to do this, but you can use an icing sugar dredger if you have one.)

Cut into portions and serve!