Wash and dry the figs. Cut figs in half and fan open. Take the puff pastry circles, place on baking tray. Place four halves of fanned figs per tart, leaving 1cm border around. Share butter equally in little knobs over each tart and dust with icing sugar. Cook in oven for about 5 to 6 minutes until pastry is cooked.
During the cooking time, make the sabayon.
Put the caster sugar in a saucepan with a little water and cook on a medium heat. Whisk the egg yolk until white and fluffy and then pour the boiling sugar syrup over the egg yolk and whisk until cold. Add the cinnamon and fold in the lightly whipped cream.
When the tarts are cooked, remove from the oven, place a large spoonful of sabayon over each tart and glaze under a hot grill.