Preheat the oven to 350°F (175°C). Grease a baking pan (9x9 inches) or line with parchment paper.

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

In another bowl, cream the softened butter, brown sugar, and granulated sugar until light and fluffy.

Beat in the egg and vanilla extract until well combined.

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

Fold in the chocolate chips and nuts (if using).

Spread the batter evenly in 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 for 10 minutes before transferring to a wire rack to cool completely.

Cut into bars and serve.