Ingredients

Step by step

1. Lightly butter and line a 20cm square cake tin very neatly with baking paper. Ideally use a straight-sided tin as you will then have perfect squares, but if not, use a brownie or traybake tin and trim the edges once cooked to make them perfectly straight and square.
2. Preheat the oven to 180°C, fan 160°C, gas 4. Put the butter and sugar in a mixing bowl and beat until really light and creamy. Beat in the eggs a little at a time, then stir in half the flour with the lemon zest and the ground almonds. Fold in the remaining flour and spread the mixture evenly in the cake tin.
3. Bake the cake for 45-50 minutes until golden brown and firm to the touch in the centre. Allow to cool in the tin for 10 minutes, then turn upside down, remove the tin and cool on a wire rack. Refrigerate for 4 hours or overnight to get completely firm before cutting.
4. To make the buttercream, mix the butter and icing sugar together with a drop of boiling water to give a smooth spreadable icing.
5. When the cake is completely cold, flip the cake back over so you can trim the top level with a sharp knife if it's not completely flat. Then turn the cake upside down again, so the flat base is uppermost, and peel off the paper. Brush thinly with apricot glaze.
6. Dust the worktop with icing sugar and roll out the marzipan very thinly to a 20cm square and place on top of the cake, trimming it to fit. Spread the 4 sides of the cake thinly with buttercream as neatly as you can – this will make sure the fondant icing looks smooth when poured over.
7. Cut the cake into 4cm-wide strips (note: if you use a brownie tin the strips will be slightly smaller – about 3.5cm) and spread the sides of each strip thinly with buttercream. Cut each strip into 4cm squares (or 3.5cm) this will give you 24 cakes. Spread the cut sides of each cake neatly with more buttercream.
8. Chill the cakes in the fridge for 30 minutes, then, if necessary, neaten up the butter cream edges.
9. Meanwhile, sieve the fondant icing sugar into a bowl. Squeeze the juice from the zested lemon, then strain it through a fine sieve into a small bowl. Add 2 tablespoons to the icing sugar with enough warm water (you will need about 100ml) until it is a very thick pouring consistency. Test it by pouring a little over the back of a wooden spoon – it should coat it thickly. Divide the icing into 2 bowls and add a little colouring to each, until you have the shade that you want.
10. To coat the cakes, place them on a wire rack over a tray to catch the drips, leaving some room between them. Spoon about a dessertspoonful of fondant icing over each one, then with a small palette knife spread the icing down the sides (it won't look as thick on the sides as there is no marzipan underneath). Decorate with little sugar butterflies and leave to set for half an hour. Put inside fairy cake cases, fold up the sides to make squares and leave to set for another 30 minutes before serving.