Cut the butter into 4 pieces and put in a long dish.
Micro wave on HIGH for 40 seconds to soften.
Put the 2 egg yolks and whole egg into a bowl, add the cane sugar syrup and whisk.
Add the flour and yeast, still whisking, then the softened butter.
Continue to whisk until the mixture is smooth and shiny.
Add the preserved orange zest (peel).
Whisk the egg whites to firm peaks and fold carefully into the mixture.
Pour the mixture into the long dish in which the butter was softened.
Smooth the surface.
Microwave on MEDIUM-HIGH for 10 minutes.
Remove the dish from the oven and leave to stand for 30 minutes.
Mix together the orange juice, confectioners' (icing) sugar and curagao liqueur and use to frost (ice) the cake.
Refrigerate for 2 hours.
Peel the oranges, removing all white pith and membranes, and slice finely in rounds, then cut each round in half.
Arrange decoratively along the top of the cake.
Melt the apricot preserve in a small bowl for 1 minute on HIGH.
Pour the melted preserve over the cake through a strainer (sieve), pressing down with the back of a wooden spoon.