Preheat your oven to 160ºC/140ºC fan.
Line two 20cm round sandwich tins with greaseproof paper.
Put all of the cake ingredients into a large bowl.
Beat until all of the ingredients are combined.
Split the mixture between the two prepared tins.
Then bake for 30-35 minutes until a skewer inserted in the centre comes out clean.
Remove the cakes from the oven and leave them to cool.
Make the coffee buttercream icing whilst the cakes are cooling.
Mixing together the instant coffee powder/granules with the boiling water then set aside to cool.
In a large bowl beat the butter and vanilla extract until soft.
Add the icing sugar and mix until the mixture is smooth.
Gradually add the coffee mixture.
Place the bottom layer of your coffee sponge onto a dish.
Spread about ⅓ of the coffee buttercream evenly across the sponge.
Add the top layer of sponge and spread ⅓ of the coffee buttercream on top.
Put the remaining buttercream into a piping bag.
Pipe blobs of buttercream evenly spaced around the edge of the cake.
I added coffee beans just to make it look fancy.