How should I make this cake?

I think you should make a Watergate Cake. That's what I thought of when reading your comments. The link below is for a Watergate cake that sounds like the one my friend's mother used to make for us, including the second box of pistachio pudding in the Cool Whip for the frosting. But allrecipes.com has other Watergate cake recipes you can choose as well.

You should make him a pistachio pie. You make the pudding and stir in a thing of cool whip, it is yummy and easy.

How about this:

Pistachio Trifle

Cake: White cake mix- 1 pkg instant pistachio pudding- 1 cup club soda- 1/2 cup chopped nuts- 1/2 cup oil- 4 eggs- 1 teaspoon vanilla

Filling:

2 packages instant pistachio pudding 1 (12 oz) container of cool whip

Mix all cake ingredients & pour into 9 by 13 pan. Bake 350 30-35 minutes (check with toothpick), cool. Divide in half, placing half of cake (broken into large pieces) into trifle bowl. Following pudding directions mix 2 pkgs of pistachio pudding together. Pour half of pudding over cake pieces. Spread one-half container of coolwhip over cake. Repeat with cake, remainder of pudding then rest of container of coolwhip. Can sprinkle top with crushed walnuts. Refrigerate a few hours before serving.

jello pistachio pudding cake recipe

type that into Google; you get a million ideas/recipes. see which one you think your friend would like.

You could do either or both. Maybe a simple vanilla frosting with some crushed pistachios sprinkled on top.

You can layer your cake and put the pistachio pudding in the cake. Then take another package of instant pistachio pudding and make the recipe and then mix it with equal amount of Cool Whip and spread that between the cake layers and around the outside. Top the cake with sprinkles of pistachio nuts.

It should be a hit.

Hope that helps.