1. Preheat your oven to 160°C. Grease a 9 inch/23cm tart case and set aside.
2. In a mixing bowl, beat together the butter and sugar until light and fluffy. Gradually mix in the flour salt and vanilla until the dough comes together.
3. Cut off 1/4 of the dough, cling film and place in the fridge until later. Press the other 3/4 dough into the bottom of the tart case. Gently push the pastry into the tin, pressing gently into the edges. Bake for 20 minutes or until the crust is golden brown. Remove from the oven and leave to cool for 10 minutes.
4. Evenly spread the Blueberry & Coffee Jam on the shortbread base making sure to leave a 15mm edge all the way around.
5. Take the other 1/4 shortbread and crumble the dough into small pieces over the jam.
6. Return the shortbread to the oven and continue baking for 30 minutes or until the topping is golden brown. Remove from the oven and leave to cool completely. Serve alone or with ice cream or custard.
