Preheat the oven to 180c fan
Add the flour and butter in a bowl and rub together with your fingertips until it resembles breadcrumbs.
Mix in the icing sugar, then add the egg yolk and orange juice. Bring together to form a dough. Roll the dough into a ball then flatten out into a disc shape, wrap in clingfilm and chill in the fridge for 30 mins.
Grease a 12 cup bun tray. Roll out the dough to about the thickness of a £1 coin. Cut out 12 circles big enough to line the holes in the tin. With the pastry you have left, cut out 12 crowns, or whatever shape you like and place on a lined baking sheet.
Fill the pastry cases with marmalade and bake for 15 - 18 mins.
Leave the tarts in the pan on a wire rack to cool completely.
Bake the pastry shapes for 10-15 mins or until nicely browned.
Leave to cool on a wire rack.
In a bowl, whip the cream, icing sugar and vanilla until medium to stiff peaks, being careful not to over whip.
Pipe a swirl onto each cooled tart and place the pastry crown.
Zest an orange over the tarts.