Creating Watergate Cake can be a straightforward process if you follow these steps:

1. Preheat the Oven: Set your oven to 350°F (175°C). Grease and flour a 9×13-inch baking pan.
2. Mix Dry Ingredients: In a large mixing bowl, combine the yellow cake mix and the instant pistachio pudding mix.
3. Add Wet Ingredients: Add the drained crushed pineapple, vegetable oil, and eggs to the dry mixture. Mix well until the batter is smooth.
4. Fold in Nuts: Gently fold in the chopped nuts until evenly distributed throughout the batter.
5. Pour Batter: Transfer the batter into the prepared baking pan, spreading it evenly.
6. Bake: Place in the preheated oven and bake for 30-35 minutes or until a toothpick inserted in the center comes out clean.
7. Cool the Cake: Remove from the oven and allow the cake to cool in the pan for about 30 minutes.
8. Prepare the Frosting: In a medium bowl, mix the cool whip, powdered sugar, and vanilla extract until combined and smooth.
9. Frost the Cake: Once the cake is cool, spread the frosting evenly over the top.
10. Chill: For best results, refrigerate the cake for at least one hour before serving to allow the flavors to meld.

These steps will guide you in creating this incredible Watergate Cake effortlessly.