Lightly spoon flour into a measuring cup and level off.
In a large bowl, blend together, 2 cups flour, oats, brown sugar, baking soda, salt and butter. Blend at low speed until crumbly. Press half the mixture into the bottom of the greased pan. Reserve the remaining crumb mixture for topping.
Bake at 350 degrees for 10 minutes.
Meanwhile, in a small bowl combine the caramel topping and the 3 tablespoons flour. Set aside.
Sprinkle warm crust with chocolate chips and nuts. Drizzle evenly with caramel mixture; sprinkle with the remaining crumb mixture. Bake an additional 18 to 22 minutes or until golden brown.
Cool completely. Refrigerate 1 to 2 hours until filling is set. Cut into squares or bars.
