Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 10 inch Bundt pan.
In a medium bowl, stir together the cake mix and 1 package of instant pudding. Add the oil, eggs and club soda, mix well. Fold in the chopped nuts, reserving some for garnish if desired. Pour into the prepared pan.
Bake for 50 to 60 minutes in the preheated oven, until cake springs back when lightly touched. Cool for 10 minutes in the pan before inverting onto a wire rack to cool completely. In a medium bowl, stir together the instant whipped topping and instant pudding. Add the milk and mix until light and fluffy. Slice cooled cake into layers, fill and frost including the hole in the middle. Garnish with nuts if desired. Keep chilled until serving.