In a bowl mix flour, sugar and baking powder. Make a well in the centre and add eggs and oil. Mix quickly with a spatula first, then with your hands until you make a ball of dough. Wrap in cling film and refrigerate for 30 minutes.
Preheat the oven to 180 C / Gas 4.
Remove 2/3 of the dough from fridge. Place in between 2 sheets of parchment and roll out to a 5mm thickness and in a 26-28cm circle. Transfer to a 23-25cm tart tin with one parchment sheet on the bottom. Lift the edges to make a shell. Pour the orange marmalade over the pastry and spread evenly.
Remove the remaining dough from the fridge; roll out and cut 8 to 10 strips. Place over the top of the tart in a lattice pattern, pinching the edges of the pastry together to seal and cutting away any excess.
Bake in the preheated oven for 30 minutes or until the pastry is golden. Remove from oven, cool and serve.