• Preheat the oven to 350F/180C/160C Fan. Grease a 20cm by 20cm (8 inches by 8 inces) square tin or line it with baking parchment.
• Measure all the ingredients for the cake into a large mixing bowl. (Remember to sieve the flour to remove any flour clumps.)
• Beat with an electric whisk until the mixture is light and airy. You may need to keep scraping down the sides of the bowl until everything is incorporated.
• Add the mixture to the tin and level it off. Pop it into the oven and cook for 30 minutes. The cake is done when it comes away from the sides of the tin or a skewer inserted in the middle comes out with only a few crumbs attached.
• Remove from the oven and leave to cool for at least 5 minutes before attempting to remove it from the tin. It will be a little fragile straight out of the oven. Leave to cool completely on a cooling rack.
• Once it is cool. Make the buttercream icing.

Making the Buttercream Icing

• In a large mixing bowl, measure out the softened unsalted butter. Beat the butter for about 4 minutes until it is lighter in colour and smooth. An electric whisk is best for this but a wooden spoon will do the job.
• Add half the amount of sieved icing sugar and mix this in. Beat for at least another 4 minutes.
• Add the remaining icing sugar and repeat the process.
• Add the remaining ingredients, the vanilla, the cinnamon and the muscovado sugar (if using) and beat again until it is smooth and uniformly coloured. This should only take a couple of minutes.
• Use this buttercream to decorate the cake. Spoon small amounts all over the cake if you are intending to make a simple pattern with a fork or a palette knife. Then smooth it out with a palette knife and begin to make you pattern in the buttercream. Otherwise, fill your icing bag, selelct your favourite icing nozzle and decorate that cake.