To make an easy Jell-O pistachio pudding cake, combine 1 box yellow cake mix with 1 package instant Jell-O pistachio pudding mix. Add 4 eggs, 1 cup club soda and 1/2 cup canola oil, and beat the batter on low speed for 30 seconds, followed by medium for two minutes.
Stir 1/2 cup chopped walnuts into the cake batter before pouring it into a greased, floured 10-inch tube pan. Bake the cake for 40 to 45 minutes at 350 degrees Fahrenheit. Allow the cake to cool for 10 minutes, remove it from the pan, and allow it to cool completely. While the cake cools, make a pistachio pudding icing by mixing 1 cup heavy whipping cream with 1 package instant pistachio pudding mix and 2 teaspoons confectioners sugar.
For a slightly different take on this cake, mix 1 box of cake mix with 1 package pistachio pudding mix, 1/2 cup orange juice and 1/2 cup water. Add 1/2 cup vegetable oil and 4 eggs. Beat the batter for two minutes on medium-high. Pour three-quarters of the batter into a greased and floured bundt pan. Add 3/4 cup chocolate syrup to the rest of the pistachio cake batter, and mix it thoroughly. Pour the chocolate-pistachio batter on top of the other batter, and bake the cake for 60 minutes at 350 F.