Preheat oven to 375 degrees F (195 degrees C). Grease a 9×9 inch baking pan.
In a medium bowl, mix together the flour, brown sugar, and white sugar. Cut in the 1/2 cup of butter until mixture resembles coarse crumbs. Pat into the bottom of the prepared pan.
In the same bowl, stir together the eggs and brown sugar, stir in the coconut and walnuts until everything is gooey. Spread evenly over the crust layer, and bake for 25 to 35 minutes, everything should be golden brown.