Preheat oven to 350° F. Spray non-stick spray into bundt pan.
Combine cake mix, pudding mix, eggs, club soda and canola oil into a large bowl. Beat mixture on medium speed for 2 minutes. Add in walnuts and stir.
Transfer mix to prepared bundt pan.
Bake 40-45 minutes or until toothpick comes out clean from the center.
Cool in pan 10 minutes before transferring to plate.
For Frosting: Combine pudding mix and milk in large bowl. Beat mixture on low for 1 minute.
Fold in thawed whipped topping.
Spread over cake.
Refrigerate until serving.