Preheat a baking sheet in the oven to 200C/400F/Gas 6.
For the pastry, place all the ingredients into a food processor and blend together, until the mixture resembles fine breadcrumbs.
Add enough cold water to bind the mixture together and shape into a ball. Remove from the food processor and shape into a bowl.
Using a rolling pin ,roll out the pastry into a large disk, the thickness of a one pound coin.
For the frangipane, place all the ingredients into a food processor and blend together.
With a palette knife, spread the frangipane mixture over the pastry disk, and fold the edges in to create an edge.
Slide the tart onto the baking sheet and transfer into the oven for 10 minutes, or until the pastry is golden.
To serve, transfer the tart onto a serving plateand dust with the icing sugar.