Preheat oven to 325 degrees. Grease and flour a 13 x 9-inch pan; set aside.
CAKE: In a large bowl, beat eggs using an electric hand mixer on high speed for 2 minutes. Add sour cream, water, cream of coconut, and vanilla extract; beat until well combined. Add cake mix; beat on low speed just until blended. Increase speed to high, beat for 2 minutes more.
Pour batter into prepared baking pan. Bake for 40 to 45 minutes or until a wooden toothpick inserted in center comes out clean. Cool cake in pan on a wire rack. Once cooled, cover the pan with plastic wrap, and freeze the cake for 30 minutes.
FROSTING: In a medium bowl, beat cream cheese and butter on medium speed until creamy; add milk and vanilla, beating well. Gradually add confectioners’ sugar, beating until smooth. Stir in coconut.
Remove cake from freezer. Spread with Coconut Cream Cheese Frosting. Cover and store in refrigerator until ready to serve.
Cook’s Note: If desired, this cake can be baked in a greased and floured 15 x 10-inch jellyroll pan for 30 to 32 minutes or until a wooden pick inserted in center comes out clean.
Coco Lopez cream of coconut can be found in the "mixer aisle" near beer and wine in most major grocery stores.