In a large bowl, whisk together cake mix, water, eggs, and oil until smooth and lump-free

Pour the batter into the prepared dish and spread evenly to the edges

Bake until a toothpick inserted in the center comes out with a few moist crumbs and the surface springs back lightly

Allow the cake to cool completely in the pan until it reaches room temperature

In another bowl, beat the softened cream cheese until silky and smooth with no lumps

Add the vanilla and pistachio pudding mixes and continue mixing until fully combined

Pour in the milk gradually while mixing, creating a thick and creamy filling

Spread the pudding mixture evenly over the cooled cake, ensuring full coverage

Spoon the drained crushed pineapple across the top, distributing it evenly

Gently spread the whipped topping over everything, creating a smooth final layer

Refrigerate for at least 4 hours until fully set and chilled before slicing