Preheat the oven to 350°F (175°C).

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.

Add the egg and vanilla extract to the butter mixture and mix until combined.

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

Fold in the chocolate chips and walnuts.

Drop tablespoon-sized balls of dough onto a baking sheet lined with parchment paper.

Bake in the preheated oven for 10-12 minutes, or until the edges are golden brown.

Allow cookies to cool on the baking sheet for a few minutes before transferring to a wire rack to cool completely.