2Combine the base ingredients: the cake mix, oats, margarine, and egg. Beat on low speed until blended and 'crumbly'. Press into the bottom of the prepared pan.
3In a bowl, combine the frosting, cream cheese and egg at low speed until well-blended. Beat at high speed until smooth. Stir in nuts (or you can wait and sprinkle them across the top before baking).
Spread this mixture over the crumbled base.
4Bake at 350° for 40 - 45 minutes, until firm.
5Cool completely, then sprinkle with powdered sugar.
Cut into 36 bars.