If serving cold, refrigerate, whisking occasionally until it is fully chilled, to keep it smooth.
Bring to a boil, whisking occasionally, to form a smooth mixture.
Pass through a fine mesh strainer, whisking occasionally to help the liquid pass through.
Cook over a gentle heat for a further 10-15 minutes, or until thick and glossy, whisking occasionally.
Pour dressing into a bowl, and allow to cool, whisking occasionally.
Reduce heat and simmer for five minutes, whisking occasionally.
Heat over medium heat until blended, whisking occasionally.
Place over medium heat, whisking occasionally, until hot but not boiling.
Remove the custard from the heat and cool, whisking occasionally.
Heat until the sugar and almond paste are dissolved, whisking occasionally.