Lemon Squares

Directions

1. 1
   Preheat the oven to 350F.
2. 2
   To make the crust, mix together the baking mix, xanthan gum, and salt in a medium bowl.
3. 3
   In the bowl of a stand mixer, cream together the shortening and sugars, Stir in the vanilla, Mix in the dry ingredients until they are thoroughly combined, then press the dough into a 9x 13-inch baking pan.
4. 4
   Chill the crust in the refrigerator for 20 minutes.
5. 5
   Remove the crust from the refrigerator and prick it all over with a fork.
6. 6
   Bake the crust for 20 minutes, or until lightly browned.
7. 7
   Transfer the baked crust from the oven to cooling racks and cool for at least 30 minutes.
8. 8
   Maintain the oven temperature.
9. 9
   While the crust is cooling, make the filling.
10. 10
    In a medium saucepan, whisk together 3 cups of the confectioners sugar and the cornstarch.
11. 11
    Continue whisking and slowly add the water.
12. 12
    Whisking constantly, bring the mixture to a full boil over medium-high heat (8 to 10 minutes), Sprinkle the gelatin over the boiling mixture and stir to dissolve it.
13. 13
    Reduce the heat to medium and continue cooking, stirring constantly, for another 5 minutes; the mixture should be quite thick, Remove the custard from the heat and stir in the lemon juice and zest.
14. 14
    Pour the lemon custard mixture over the cooled crust.
15. 15
    Bake for 30 minutes.
16. 16
    Remove from the oven and let cool completely in the pan on a cooling rack, Dust with confectioners sugar and cut into squares for serving.
17. 17
    Store the lemon squares in an airtight container and refrigerated for up to 3 days.