Instant pudding doesn't have the same consistency as the cook and serve, and the cake mix needs to be "just add water". If there are multiple packets in the Angel Food Cake Mix Box it won't mix ...
Melt the butter in the microwave, about 1 minute. In a large bowl add the yellow cake mix, the first box of instant pistachio pudding mix, eggs, club soda and melted butter. Stir until fully mixed ...