Pre-heat the oven to 350 and liberally spray an 8 x 8 baking pan with cooking spray. In a mixing bowl, combine the flour, melted butter, powdered sugar and vanilla for the crust. Stir it together thoroughly until it resembles wet sand. Pour the mixture into the baking pan and press it down firmly in an even layer to form the bottom crust. Bake it for 20 minutes, until lightly golden and set.
While the crust bakes, make the easy filling. Combine the lemon zest, lemon juice, sugar, baking powder, eggs and salt in a bowl. With a hand mixer, whip it all together until smooth. Fold in the shredded coconut with a spatula to finish it. Take the crust out when it is done and pour the filling over it. Even it out with the spatula.
Bake the lemon coconut bars for another 20 minutes, until the filling is completely set and starts to get slightly golden on top. Take the pan out and let it cool for a few minutes. Top with a generous dusting of powdered sugar and then serve!