Preheat oven to 350 degrees Fahrenheit. Grease a 9x13 inch pan and set aside.
In a large mixing bowl add the 1 (16-ounce) box yellow Cake Mix, 1 large egg, and ½ cup melted unsalted butter and stir together until incorporated. Press into the bottom of your 9x13 inch pan. Set aside.
To make the filling:
In a large mixing bowl beat the 1 (8-ounce) softened cream cheese until smooth. Add 2 large eggs one at a time and continue to beat until smooth. Add 1 teaspoon vanilla extract, ½ cup fresh lemon juice, 2 cups powdered sugar, and ½ cup melted unsalted butter. Pour over the cake mix.
For the topping:
In a medium sized bowl combine the ¼ cup light brown sugar and ¼ cup granulated sugar. Mix in the 1 cup sweetened shredded coconut flakes and stir in the 2 tablespoon melted unsalted butter and ¼ cup flour. Sprinkle on top of the filling.
Bake in preheated oven for 35-40 minutes. You want the center to be gooey but set and the top is lightly brown. Allow to cool before cutting into squares.