2) Line a 15cm tin with greaseproof paper and half-fill with the mixture. Bake in the centre of the oven for 50 minutes. Test before removing to ensure the cake is cooked all the way through; a knife should come out clean and the top should bounce back when pressed.
3) Allow to sit in the tin for five minutes then remove the lining and place on a cooling rack. Allow to cool completely then remove the top and slice into three even layers with a leveler or a large knife.
4) Make the icing by mixing together the icing sugar, butter and cream cheese until very light and fluffy.
5) Layer your sponge with jam and cream cheese icing inside, stacking up the layers. Coat liberally with cream cheese icing all over the sides and top, then use the palette knife to make large strokes to add some texture to your cake.
6) Top with the crystallised blueberries and a sprig or two of seasonal blossom.
For the crystallised blueberries:
1) Separate the egg white, put the caster sugar into a bowl and lay out a sheet of greaseproof paper.
2) Dip the blueberries into the egg white and then into the sugar. Lay on the paper to dry for 60 minutes.