Valentine's heart biscuits

Pre-heat the oven to 180 C / Gas 4. Grease a baking sheet with a little butter and sprinkle with flour.

Wash and zest the lemon. Juice half the lemon and strain through a tea strainer.

In a food processor whiz the butter and flour to breadcrumbs. Add 75g of the caster sugar, the lemon zest, juice and the egg yolk and blitz to a dough.

Transfer the dough to a floured surface and roll it into a 5mm thick disc. Using an 8cm heart-shaped biscuit cutter cut 6 hearts. Place the hearts on the prepared baking sheet.

Bake biscuits for 15 minutes. As soon as the biscuits are cool enough to handle transfer to a wire rack.

Meanwhile prepare the filling. Put the cranberries in a pan with the remaining caster sugar and cook over a low heat for 5 minutes. The berries have to be soft but still retain their shape. Remove from the heat, add the rum, if using, and set aside to cool.

To assemble the hearts, place one biscuit on a dessert plate, add a quarter of the cranberries, cover with another heart, add another quarter of the cranberries and finish with another biscuit. Dust with icing sugar and drizzle with some of the cranberry juice. Serve with a dollop of mascarpone.