Preheat the oven to 350°F (175°C). Grease and line a baking pan with parchment paper.

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

Add the eggs one at a time, mixing well after each addition, 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 if using.

Spread the batter evenly into the prepared baking pan.

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

Allow to cool in the pan for 10 minutes before transferring to a wire rack to cool completely.

Cut into bars and serve.