In a medium mixing bowl, whisk together the vanilla pudding, milk, and sour cream until smooth and it begins to thicken. Set aside. Cut the angel food cake into 1-inch cubes and then evenly layer half of it into the bottom of the baking pan.
If you have any leftovers, you can either transfer them to an airtight container or tightly wrap the dish with plastic wrap. Afterward, transfer them to the refrigerator and enjoy the leftovers for up to 2 days. I find any longer than 2 days, the cake starts to become soggy.