Preheat the oven to 350°F (175°C) and grease a 9x13 inch baking pan.

In a mixing bowl, cream together the softened butter, brown sugar, and granulated sugar until smooth.

Beat in the eggs one at a time, then stir in the vanilla extract.

In a separate bowl, whisk together the flour, baking soda, and salt.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

Fold in the chocolate chips and walnuts.

Spread the batter evenly into the prepared baking pan.

Bake in the preheated oven for 20-25 minutes, or until the edges are golden brown and a toothpick inserted in the center comes out clean.

Allow to cool in the pan before cutting into bars.