Add margarine, sugar and vanilla extract to a mixer bowl and mix on medium until well combined.
Beat in in eggs, one at a time until well blended.
In a separate medium bowl whisk together flour, baking powder and salt.Add the flour mixture to the mixer bowl and mix on low until well combined. Pour batter into a greased + parchment lined 9x13x2 baking pan and spread out evenly. Top with chocolate chips and nuts. Bake for 30-35 min for dark coated pans or 35-40 min for regular or glass pans.Remove and let cool completely.Transfer to a cutting board and cut into squares/bars.(If you're giving these as gifts or using on a cookie tray for guests, I suggest cutting away the crispier edge around the outside then cutting into squares/bars then promptly eating all removed crispy edges to hide the evidence! haha) Store in well sealed container or freeze until needed.