Roll the pastry out thinly on a lightly floured surface, then stamp out 24 × 6 cm (2½ inch) circles with a fluted biscuit cutter and press into the buttered sections of 2 × 12-section mini muffin tins. Reknead and reroll pastry trimmings as needed. Chill for 15 minutes.
Put the butter, sugar, syrup, lemon rind and juice in a small saucepan and cook over a low heat until the butter has just melted and the sugar dissolved. Take off the heat and leave to cool slightly.
Stir the beaten egg and breadcrumbs into the syrup mix and beat until smooth. Spoon into the pastry cases.
Bake in a preheated oven, 180°C (350°F), Gas Mark 4, for 15 –20 minutes. Leave to cool for 15 minutes, then loosen the tarts with a knife and remove from the tins. Transfer to a wire rack and leave to cool slightly. Serve warm with spoonfuls of whipped cream sprinkled with ground cinnamon.