Grease a 9 x 13 glass dish. Prepare white cake mix per package instructions and pour into the greased baking dish. Baked as directed on the box.
Remove baked cake from oven and immediately poke holes all over the warm cake with the handle of a wooden spoon.
Pour entire can of condensed milk over the top of the warm cake, letting it run into the holes. Then cover and refrigerate until cool (several hours).
Place the prepared frosting into a bowl and whip on a very high speed for about 5 minutes You are aerating this cream cheese frosting to make it lighter.
Frost the cake with the whipped frosting and then sprinkle the coconut all over the top.
Cut the cake and enjoy! Keep covered with plastic wrap and it will stay fresh all week.