Preheat the oven according to the back of the box.
Prepare cake mix as back of the box states. I personally like to swap out the water called for and use milk instead, as well as add an extra egg. It makes it taste more homemade, but this is completely optional.
Bake according to directions on back of the box. Once the cake comes out of the oven, poke holes all over it using the handle of a wooden spoon.
Whisk together the sweetened condensed milk with 1¾ cup milk. Mix in the white chocolate pudding mix, and allow the mixture to stand for 1 minute. Pour the mixture over top of the hot cake, making sure to get the pudding mixture in all of the holes. Let the cake cool completely, and then frost with cream cheese icing (homemade or 2 cans of store bought).
Store in the refrigerator.