Preheat your oven to 350°F (175°C). In a large mixing bowl, combine the Golden Butter Cake Mix and sugar. Add the required ingredients as per the cake mix instructions, typically eggs and water. Using an electric mixer, beat on medium speed for about 2 minutes until the batter is smooth and well combined.
Pour the batter into a greased 9x13 inch baking pan. Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted in the center comes out clean. Once baked, remove from the oven and let it cool in the pan for about 10 minutes before transferring to a cooling rack.
While the cake is cooling, prepare the frosting. In a mixing bowl, combine the thawed Cool Whip and sour cream. Gently fold the mixture together until well combined. You can add a bit of sugar if you prefer a sweeter frosting, but the sweetness from the Cool Whip usually suffices.
Once the cake is completely cooled, spread the sour cream frosting evenly over the top. Make sure to cover the cake all the way to the edges for a beautiful finish.
Sprinkle the sweetened coconut evenly over the frosted cake, ensuring each slice will have a delightful coconut topping.
For the best flavor, let the cake chill in the refrigerator for at least an hour before serving. This will help the flavors meld together beautifully.