Heat oven to 350°.
Grease baking pan, 13 x 9 x 2 inches.
Mix oats, flour, brown sugar and baking soda; stir in margarine.
Reserve 3/4 cup of the oatmeal mixture.
Press remaining oatmeal mixture in pan.
Bake 10 minutes; cool 5 minutes.
Prepare Brownies as directed except€”omit nuts.
Spread dough over baked layer.
Sprinkle with reserved oatmeal mixture.
Bake until brownies begin to pull away from sides of pan, about 30 minutes. (Do not overbake.) Cool; cut into about 1 1/2-inch squares.