Preheat the oven to 350°. Place butter in an 8x8x2-inch pan, then place in the oven until melted, about 3 minutes.
In a medium bowl, combine flour, confectioners’ sugar, and pecans. Add the flour mixture to the melted butter, then combine the ingredients with a fork. Pat down in an even layer in the pan. Bake 18 minutes, until slightly browned.
Combine sugar, eggs, zest, juice, and flour. Just before you remove the crust from the oven, add the baking powder to the lemon mixture. Pour the lemon mixture over the baked crust and return to the oven another 15 minutes.
Remove the pan from the oven and sprinkle coconut over the surface. Return the pan to the oven another 10 minutes. Remove the pan and cool on a baking rack. Cut into squares just before serving.