Coffee and rum tiramisu with molasses topping

Method

1. Mix the coffee with the rum and 2 teaspoons of the molasses sugar. When the sugar has dissolved, pour it into a small, shallow dish.
2. Set aside 2 tablespoons of the caster sugar. Beat the egg yolks and the remaining caster sugar together in a bowl for about 4 minutes until pale, thick and moussey.
3. Beat the mascarpone cheese in another bowl until smooth, then beat into the egg yolk mixture, along with the vanilla extract. Whisk the egg whites in a bowl until just beginning to show signs of stiffening, then gradually whisk in the reserved caster sugar to form a soft but not too stiff meringue. The tips of the peaks should fall over, not stand upright. Gently fold into the mascarpone mixture.
4. Briefly dip half the sponge fingers, one at a time, into the coffee mixture and lay them side by side on a flat, rectangular serving plate. Spoon over half of the mascarpone mixture and spread out evenly. Cover with another layer of coffee-soaked sponge fingers and the rest of the mascarpone mixture. Chill in the fridge for 1½ hours.
5. Mix the remaining molasses sugar with the dark muscovado sugar – much like you would when making pastry, rubbing the grains through your fingers to remove any lumps. Then sprinkle it over the top of the dessert and chill for another 15-20 minutes to allow time for the sugar to dissolve before serving.