Blitz the butter, flour and ginger, if using, in a food processor until the mix looks like fine crumbs. Stir in the sugar, then add the egg yolk and 2 tsp cold water. Pulse until the dough clumps together, or bring it together with a knife by hand. Turn onto a lightly floured surface and press into a smooth round. Chill for 30 mins or until firm.
Roll out the pastry to the thickness of 2 x £1 coins and stamp out 8 x 11cm circles (or cut around a saucer and trim to fit tins). Line 8 x 10cm width heart-shaped tins with the pastry. Re-roll trimmings. With a small cutter, stamp out 8 hearts to decorate. Chill tins and hearts for 15 mins or until firm. Heat oven to 170C/fan 150C/gas 5 and put a baking sheet in.
Stir the syrup, lemon juice and zest together. Divide the breadcrumbs between tins (they should reach to the top of the pastry), then spoon the syrup over slowly, adding more once the first lot has started to soak in. Top with the small pastry hearts. Put tins onto the hot baking sheet and bake for 25 mins or until pastry is golden and the filling is orangey-gold and slightly set. Leave to cool for 15 mins, then turn onto a wire rack. Serve just warm. Will keep for up to 3 days in an airtight container. Heat in a low oven for 5 mins to warm through.