In a bowl, combine cake mix, eggs, oil and pumpkin spice. Stir with wooden spoon until combined. It will be thick.
Add chocolate chips and nuts, if using. Stir.
Line a 9×13 (or 9×9 if you want a thicker bar) pan with foil, leaving some hanging over the edge to make “handles”; spray with non-stick cooking spray.
Spread batter into pan and press with fingers to even it out.
Bake at 350 degrees F. for 28-30 minutes for 9×13 pan or 35-40 minutes for 9×9 pan.
Lift the “handles” to remove bars from pan. Cut into squares.
Recipe by Mandy's Recipe Box at https://mandysrecipeboxblog.com/chocolate-chip-pumpkin-spice-bars/