Blood Orange Squares

Directions

1. 1
   For the Crust:
2. 2
   Position a rack in the center of the oven and preheat to 350F.
3. 3
   In a food processor, pulse together all the ingredients for the shortbread until the mixture just begins to hold together in large pieces.
4. 4
   Turn the dough out into a 9-by-13-inch baking pan and press it into a single layer covering the bottom of the pan.
5. 5
   Smooth the top with a rubber spatula.
6. 6
   Bake on the center rack, rotating the pan halfway through, until golden and firm to the touch, 20 to 25 minutes.
7. 7
   Remove from the oven and reserve.
8. 8
   For the Filling:
9. 9
   In a large bowl, whisk together the sugar, flour, baking powder, citrus zests, and salt.
10. 10
    In another bowl, whisk together the eggs and citrus juices.
11. 11
    Pour the liquid ingredients into the dry ingredients in two additions, whisking until smooth.
12. 12
    Spread the filling over the baked shortbread.
13. 13
    To Bake:
14. 14
    Bake on the center rack until it is just set, about 15 minutes.
15. 15
    Cool in the pan, then cut into squares.