Preheat oven to 350 degrees F. Spray a 9x13 inch baking dish with cooking spray.
Make the coconut crust. Pulse the shredded coconut in a food processor until it becomes small crumbs. Beat together the coconut with all-purpose flour, softened butter, sugar, a pinch of salt, and water until well combined. Press the crust into the prepared baking sheet in an even layer. Bake for 15-17 minutes or until golden. Remove from the oven and let cool.
Make the pineapple filling. Whisk together sugar with flour, 4 eggs, 1 egg yolk, pineapple juice, lime zest, and lime juice. Pour the filling into the crust and bake for 30 minutes or until no longer runny in the center and the edges have set. Remove from the oven and cool completely.
Garnish the pineapple coconut bars with toasted coconut and cut them into 15 bars. Sprinkle with powdered sugar if desired.