Preheat oven to 350°F. Line a 9x9x2-inch baking pan with foil, extending foil up over the edges of the pan. Lightly grease the foil. Set aside.
To prepare the crust: in a large bowl, combine brown sugar, vegetable oil spread, and baking soda; beat with an electric mixer on medium speed until well mixed, scraping side of bowl occasionally. Beat in ¼ cup of the egg product or 1 of the eggs. Beat in 1- ½ cups of the flour. Stir in the 1- ½ cups oats.
Set aside ½ cup of the oat mixture. Spread the remaining oat mixture into the bottom of the prepared pan. Bake about 12 minutes or just until crust is set.
Meanwhile, in a medium bowl, whisk together the remaining ½ cup egg product or 2 eggs, the granulated sugar, and oil. Stir in the remaining ½ cup flour, the cocoa powder, and baking powder. Stir in semisweet chocolate pieces. Pour evenly over partially baked crust. If necessary, gently spread with a metal spatula. Stir nuts and the 2 tablespoons oats into the reserved oat mixture (mixture may be a little soft). Crumble over the top of the mixture in the baking pan.
Bake for 13 to 15 minutes or until the top is puffed and set. Cool completely in pan on a wire rack. Using the edges of the foil, lift the uncut brownies out of the pan; cut into bars.
Tip: Choose Splenda® Brown Sugar Baking Blend to substitute for the brown sugar. Choose Splenda® Granular or Sweet 'N Low® bulk or packets to substitute for the granulated sugar. Follow package directions to use product amount equivalent to ⅔ cup brown sugar or ¼ cup granulated sugar. Nutrition Facts Per Serving with Substitute: same as below, except 145 cal., 16 g carb., 73 mg sodium. Exchanges: 1 other carb. Carb Choices: 1.
To make ahead: Layer brownies between waxed paper in an airtight container. Cover; seal. Store in the refrigerator for up to 5 days or freeze for up to 3 months.