Heat oven to 350. Line 13x9 inch pan with foil and then spray with non-stick baking spray.
In large bowl, beat all "Base" ingredients until crumbly. Remove 1/2 of the mixture and put in pan, pressing down to form crust. Bake 10 minutes.
Meanwhile, in small bowl, mix caramel sauce and 3 tablespoons of flour.
Sprinkle chocolate chips and nuts over baked crust. Spoon caramel sauce on top.
Sprinkle remaining crust mixture over the top. Bake at 350 for about 18-22 minutes until golden brown. Cool completely on cooling rack, about 1 hour, then refrigerate 1 - 2 hours or until filling is set.
Lift from the pan by grabbing foil. Peal foil away from sides and cut into bars. Store in tightly covered container.