Rhubarb Cardamom Shortbread Bars

Ingredients

For the Dough:

• 1 cup unbleached white flour
• 1 cup light spelt flour
• 1 tsp. baking powder
• 2 teaspoons ground cardamom
• 1 pinch of salt
• ½ pound (1 cup) unsalted butter, softened to room temperature
• 1 cup cane sugar
• 2 egg yolks

For the Filling:

• 2 cups chopped rhubarb
• ½ cup chopped strawberries and 1 tbsp red wine (both are optional but will add lovely depth of color and flavor to your filling)
• ⅓ cup cane sugar
• 1 tbsp water
• 1 tsp vanilla extract (or a vanilla bean)

Instructions

1. 1
   For the dough: Sift all the dry ingredients together in a large bowl. In a separate bowl, cream the butter until smooth and fluffy. Add the eggs yolks and sugar and mix well.
2. 2
   Gently add the dry ingredients mixture and combine the two until a soft dough has formed.
3. 3
   Being careful not to over-handle the dough, form into two balls, one just slightly smaller than the other. Wrap these in plastic wrap and freeze them for a minimum of 30 minutes. You can also keep the dough in the freezer for longer, to use at a later date.
4. 4
   For the filling: On low heat, bring the rhubarb, sugar, and water to a slow simmer, stirring often. Add the chopped strawberries and red wine if you wish (optional).
5. 5
   Cook gently for 10 to 15 minutes or until the rhubarb softens and begins to thread. The sauce should be on the thick side. If you find that the sauce is too runny after 10 to 15 minute of cooking, you can always add a teaspoon or two of tapioca flour or cornstarch to thicken it. Remove from heat and stir in vanilla. Allow the filling to cool down completely.
6. 6
   Assembly: Preheat your oven to 350 F.
7. 7
   Remove the largest of the two balls from the freezer and using the larger holes of a box grater (the side usually used for grating cheese), grate the dough directly into a greased 10 inch springform pan. Gently pat the dough into the pan.
8. 8
   Now spread the rhubarb filling evenly over the dough, leaving a little half inch edge around the perimeter.
9. 9
   Remove the second ball of dough from the freezer and grate evenly on top of the rhubarb. The rhubarb should be evenly covered, but you will see the red filling poking through.
10. 10
    Gently pat the top layer down a wee bit before tucking into the oven.
11. 11
    Bake until golden, about 30 minutes.
12. 12
    Allow the shortbread to cool completely in the pan before slicing into pieces.