Preheat the oven to 375°F (190°C). Grease a 15x10-inch jelly roll pan thoroughly or line it with parchment paper for easier removal of the cookie bars after baking.

In a medium mixing bowl, combine the all-purpose flour, baking soda, and salt. Whisk the ingredients together until they are evenly distributed. Set aside.

In a large mixing bowl, using an electric mixer on medium speed, beat the softened unsalted butter until smooth. Gradually add the granulated sugar and the packed brown sugar. Continue mixing until the mixture is light and fluffy, approximately 2 to 3 minutes.

Add the eggs, one at a time, to the butter mixture, ensuring each egg is fully incorporated before adding the next. Then add the vanilla extract and mix until combined.

Gradually add the dry flour mixture to the wet mixture, blending on low speed until fully incorporated. Take care not to overmix.

Gently fold in the semi-sweet chocolate chips and, if using, the chopped nuts until evenly distributed throughout the dough.

Transfer the dough into the prepared jelly roll pan. Spread it evenly, ensuring the dough reaches all four corners of the pan.

Place the pan in the preheated oven and bake for 20 to 25 minutes, or until the edges are golden brown and a toothpick inserted into the center comes out clean or with moist crumbs.

Remove the pan from the oven and allow the cookie bars to cool completely in the pan before cutting them into squares or bars of your desired size.