Preheat the oven to 350. Spray a 9 x 13 inch baking pan with cooking spray, then line it with 2 sheets of parchment. One measuring the width of the pan and the other measuring the length, with both sides long enough to have leftover parchment draped over the edges. This extra parchment will make "handles" after it is baked to lift it out of the pan. In a small, dry pan, toast the coconut flakes on medium-low heat for a few minutes, stirring regularly, until golden. Remove from the heatIn a large bowl, whisk together the 2 cups of flour, 1/2 tsp salt and toasted coconut.Cream the butter and granulated sugar together in a stand mixer or with a hand mixer for 3 minutes. Add the dry ingredients, a big spoonful at a time, until all in and the dough comes together.Dump the dough into the prepared pan. Use your hands to press it evenly across the surface of the pan. (It helps to spray your palms with cooking spray.)Bake the crust for 27 minutes. Remove from the oven then turn the oven to 300 degrees.
Make the Filling.
Whisk together the powdered sugar, salt and 3/4 cups of flour. Set aside.Whisk together the zest, juice, the two extracts and eggs. Pour this into the sugar mixture and whisk until well combined. Pour the filling over the par-baked crust. Carefully place the pan back into the oven. Bake for 30 minutes, or until the filling is just set. Remove from the oven and allow to come to room temperature. Then place in the refrigerator for at least 1 hour. Use the parchment handles to lift the entire bar out from the pan. Place it onto a cutting board. Cut into 16 bars, or 32 smaller bars.