Preheat the oven to 180°C/350°F/Gas Mark 4. Spray or lightly brush a 12 holed muffin tin with a little oil.
Roll the pastry out into a thin sheet, then use a large flower cutter to cut flower shapes from the pastry. Be sure to re-roll any scraps of pastry to cut out as many flowers as possible.
Push a pastry flower into each section of the muffin tin to make a cup. Pop a spoonful of blueberry jam into each cup.
Bake the tarts in the oven for around 15 minutes until the pastry is golden brown and the jam is bubbling.
Leave to cool in the muffin tin for 5 minutes or so, then finish cooling on a wire rack. Be careful when removing the tarts from the tin - the jam will be very hot!
Once the tarts are cold and the jam has re-set, decorate with the candy eyeballs and serve.