01 -
Preheat the oven to 190°C (375°F). Lightly coat a 33×23-cm (13×9-inch) baking pan with cooking spray.
02 -
In a food processor, combine the flour, 1/3 cup sugar, and salt with a quick pulse. Add the butter pieces and process until fully incorporated into a fine, dry crumb mixture.
03 -
Transfer the crumb mixture to the prepared baking pan and press into an even layer across the bottom. The mixture will appear dry but will bind together during baking.
04 -
In a bowl, toss the apple slices with lemon juice until coated. Arrange the slices in rows over the crumb mixture, drizzling any remaining lemon juice over the top.
05 -
In a small bowl, mix 1/3 cup sugar with the cinnamon. Sprinkle this mixture evenly over the apple slices.
06 -
Bake in the preheated oven for 20 minutes.
07 -
While baking, prepare the topping by mixing together the remaining 1/3 cup sugar, beaten egg, evaporated milk, vanilla extract, chopped walnuts, and flaked coconut until well combined.
08 -
Remove the partially baked base from the oven and carefully spread the topping mixture as evenly as possible over the apple layer. Return to the oven and bake for an additional 20-25 minutes until the topping turns lightly golden brown.
09 -
Allow to cool slightly, then cut into squares while still warm. Let cool completely before serving.