Preheat oven to 190°C.
For the chia jam, add fruit and orange juice to a blender and blitz until smooth.
Transfer to a bowl and add the chia seeds and maple syrup (optional).
Stir then leave aside for 5-10 minutes.
Stir again with a fork then leave aside in the fridge.
For the pastry, combined the flour, olive oil and water and mix into a rough dough.
Knead briefly until smooth.
Cover with clingfilm and chill in the fridge for 15 minutes.
Remove from fridge then roll out until 5mm thick.
Using a circular cookie or pastry cutter, cut into 16 circles.
With the leftover pastry cut out heart shapes small enough to fit snugly on top of the tart – either using a knife or heart-shaped cookie cutter and place on a baking tray lined with greaseproof paper. Re-roll pastry if necessary.
Grease tartlet tins or muffin tins with a little oil then carefully press the pastry rounds into the holes, pressing down the edges to ensure there are no gaps of air between the pastry and the tin.
Blind bake cases 10 minutes and bake tops separately for 15 minutes.
Transfer jam to cases and bake a further 20 minutes.
Add the pastry hearts on top of each tart and allow to cool before serving.