Prepare cake mix according to package directions. Bake in a 9×13 inch pan. Let cool completely.
In a medium bowl, beat cream cheese, powdered sugar, and vanilla extract until smooth.
Fold in thawed whipped topping.
Spread cream cheese mixture evenly over the cooled cake.
Sprinkle toasted shredded coconut over the top.
Chill for at least 2 hours before serving.
Notes
To toast coconut, spread in a single layer on a baking sheet and bake at 350°F (175°C) for 5-10 minutes, stirring occasionally, until golden brown.
For a pineapple poke cake variation, poke holes in the cooled cake with a fork and pour the undrained crushed pineapple over the top before adding the cream cheese mixture.