In a medium mixing bowl, whisk together the vanilla pudding mix, milk, and sour cream until smooth, and the mixture 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.
Then top it with the thawed Cool Whip, spreading it out to fully and evenly cover the pan. Using a spoon, drop spoonfuls of the remaining strawberry pie filling over the cake and swirl it around a bit.
Store leftover cake in an airtight container in the refrigerator for up to 2 days. I find any longer than that, the cake starts to become soggy.