Preheat oven to 350 degrees. Line an 8 x 8 pan with enough parchment paper so that there is some overlap on the sides (to help lift the bars out of the pan later). Spray paper with cooking spray. Set aside.
Spread coconut on a sheet pan and bake until golden brown, shaking the pan every few minutes as needed. This should take about 10 minutes. Allow coconut to cool.
Place flour, sugar and salt in the bowl of a food processor and pulse to combine. Add coconut and butter and process until the mixture resembles a fine meal. Pour into pan and press crust into even layer. Bake for 25 minutes or until crust is starting to turn golden brown.
To make the filling:
While the crust is baking, place all filling ingredients into the bowl of a food processor and mix thoroughly. Take crust out of oven and pour filling over hot crust. Return to oven and bake for another 25-30 minutes or until the center starts to spring back when touched. You may have to tent with foil about halfway through the baking time if the top of your bars is browning faster than you'd like.
Remove from oven and cool on wire rack. Cover and refrigerate for at least 3 hours.
When ready to serve, lift parchment from the pan and cut bars. Sift powdered sugar over bars, if desired.
I have made this recipe with gluten-free flour, and the results were also delicious.