Jammy Dodgers

For the biscuits: put the flour in a mixing bowl and rub in the butter until the mixture resembles breadcrumbs. Stir in the sugar and egg yolk and mix well to form a dough.

Knead until smooth, then wrap in cling film and chill for 30 minutes.

Heat the oven to 180°C (160° fan) 350°F gas 4. Line 2 baking trays with non-stick baking paper.

Roll out the dough thinly on a surface dusted with flour. Cut out rounds with a 6cm|2 1/2" cookie cutter, re-rolling the trimmings to make about 40 rounds.

Place half the rounds on a baking tray.

Cut out the centres of the remaining rounds with a 2cm|3/4" cutter and place on the other baking tray.

Bake for 10-12 minutes until golden. Cool on the trays for 2 minutes, then place on a wire rack to cool completely.

For the filling: beat the butter until very soft. Sift in the icing sugar and custard powder and beat well. Beat in the vanilla.