Amazing Coconut Refrigerator Cake

This is for a couple of friends who requested the recipe. We made it for Easter dinner this year and joked that it was a "true" Easter cake because it's best if you leave it in the fridge up to 3 days. But the longer the better!

Cake:
1 package white cake mix
1 1/3 cups water
2 tablespoons vegetable oil
3 large eggs

Coconut frosting:
2 cups sugar
2 cups sour cream (16-oz. container)
3 1/2 cups grated coconut

Preheat oven to 350 degrees. Generously grease and flour two 9-in. round cake pans. Place the cake mix, water, oil and eggs in mixing bowl. Blend with an electric mixer on low for 1 minute; stop and scrape the bowl and then mix on medium speed 2 minutes more. The batter should look well-blended. Divide the batter between the two pans. Bake the cakes until they are golden brown, about 27 to 29 minutes.

Meanwhile, prepare the frosting by combining the sugar, sour cream and coconut in a bowl, and let the mixture rest in the refrigerator until the sugar dissolves, about 1 hour. Remove the cakes from the oven and let them cool 10 minutes. Run a dinner knife around the edges and invert onto a rack and let cool another 30 minutes. When the cake is cooled, carefully slice the cake layers in half horizontally using a long serrated bread knife or a long piece of unflavored dental floss. You will have four layers. Assemble the cake by spreading some frosting on the bottom half, topping with another half, and so on until the four layers are assembled. Frost the top and sides with remaining frosting. Chill the cake, uncovered, until the frosting is firm, about 1 hour.

You can store the cake, covered with wax paper in the fridge for up to one week. The whole eggs in the batter and the sour cream frosting soaks down into the cake, making it improve as the cake chills. The coconut flavor also increases daily.