You can use any liqueur for this cake, I used Rhucello Rhubarb Liqueur. Fill with a complimentary jam or preserve to match the liqueur that you use. e.g. A lemon curd filling and a lemon food colouring would be great if using Limoncello.
Preheat the oven to 180deg Fan assisted. Grease and line the base of 2 x 8" loose bottomed sandwich tins.
Using a hand mixer, beat together the butter and sugar until light and fluffy.
While still beating, gradually add the eggs, adding a tablespoon of flour to help prevent curdling.
Gently fold in the remaining sieved flour.
Add 3 tablespoons of the Rhubarb Liqueur and mix until well combined. The remaining Liqueur will be used for soaking the cooked sponge.
Bake in the oven for 20 – 25 mins or until baked. Testing the centre of the cake with a skewer until it comes out clean.
Leave in the tins for a few moments before turning out onto a wire wrack to cool completely.
Filling a covering the cake
Brush the remaining Rhubarb Liqueur, over the two cake layers. Leave to soak while you make the buttercream.
Beat the butter until light and creamy. Gradually add the icing sugar and beat together until light, fluffy and paler in colour. This could take a few moments, much quicker if you use a hand mixer.
Add the Rhubarb liqueur, adjusting the taste as required. You just need a hint of flavour, nothing should be overpowering. Take care not to add too much liquid as this will alter the texture of the buttercream.
Gradually add the food colouring until you reach your required shade. Bearing in mind that your butter is still slightly yellow and will affect the resulting shade.
Take one of the cake layers and spread with 2 tablespoons of Rhubarb Jam. If this layer is domed slightly either turn it over or slice off the top.
Adjust the quantity of jam if needed.
Spread a little of the buttercream on top of the jam.
Sandwich the two cake layers together.
Spread the whole cake with a thin layer of buttercream – this is called Crumb Coating. Leave to set for a few moments.
Using a piping bag and your favourite nozzle, pipe the whole cake with the remaining buttercream, leaving a space in the centre for the remaining tablespoon/s of Rhubarb jam for decoration.
Notes
Using Gell colouring will not alter the texture of your buttercream, or cake batter, if using them in cake mixtures, as much as it would if you used liquid food colouring.