To make an easy, but moist coconut cake, combine 1 box of yellow cake mix with 1/2 cup of softened butter, 3/4 cup of canned coconut milk, 1/2 cup of water and 3 eggs. Beat everything together until it's combined, and transfer the batter to a greased cake pan.
Bake the batter in two greased 8-inch cake pans or one greased 9-by-13-inch pan for 30 to 38 minutes at 350 degrees, or until a knife or a long toothpick poked into the center comes out clean. Allow the cake to cool before frosting it. To make the frosting, mix 2 cups of flaked coconut with 16 ounces of sour cream, 8 ounces of thawed frozen whipped topping and 1/4 teaspoon of coconut extract. Use the frosting to fill the cake, if you're making a layered cake, and to cover the outside or top of the cake.
You can also make a moist coconut cake from scratch by combining 2 1/2 cups of cake flour with 1 teaspoon of kosher salt and 1 teaspoon of baking soda. In a separate bowl, cream 16 tablespoons of butter with 2 cups of sugar. Add 5 eggs, one at a time, and then mix in 1 cup of buttermilk and 1 tablespoon of coconut extract. Bake the cake for approximately 35 minutes at 350 degrees.