In a mixing bowl, combine the yellow cake mix, eggs, sour cream, melted butter, and half of the crushed pineapple with its juice. Mix until just combined.
Transfer the batter to the prepared pan. Bake until a toothpick inserted into the center comes out clean, about 25 to 30 minutes.
In a medium bowl, gently fold together the instant vanilla pudding mix, the whipped topping, and the remaining half of the crushed pineapple with juice.