Preheat oven to 300 degrees F (150 degrees C) with the rack in the middle of the oven.  Have ready a 6 inch (15 cm) tart pan with removable bottom. 

In the bowl of your electric mixer cream the butter and sugar until smooth (about 2 minutes).  Beat in the vanilla extract.  In a separate bowl whisk together the flours (all purpose, almond, and rice) and salt.  Add this mixture to the butter and sugar mixture and beat just until incorporated.

Press the shortbread dough evenly into the tart pan.  Prick the surface of the shortbread with a fork to prevent the shortbread from puffing up.  Using a sharp knife, score (make shallow lines) the top of the shortbread into 8 even pieces.   Gently press the flaked almonds in a decorative pattern on the top of the shortbread.

Place in preheated oven and bake until it is nicely browned (biscuit color), about 60-70 minutes.  Transfer shortbread to rack and cool for five minutes before removing from tart pan.    Place the shortbread round on a cutting board and cut into 8 wedges (along the lines scored).  Cool completely on a wire rack.

Makes 8 shortbread wedges.  Shortbreads make a wonderful accompaniment to ice creams and ices, and Fruit Fools (Rhubarb & Strawberry) (Kiwi, Blackberry or Strawberry)

Sources:  David, Elizabeth. An Omelette and a Glass of Wine. New York: Elisabeth Sifton Books Viking, Viking Penguin Inc. First American Edition 1985.

Davidson, Alan. The Oxford Companion to Food. Oxford: Oxford University Press, 1999.