Cream the butter, brown sugar and granulated sugar with an electric mixer in a large brown until smooth and fluffy. Add the vanilla and egg and mix to combine.
In a medium bowl, whisk together the flour, baking soda, and salt. Slowly add the flour mixture to the butter mixture and beat until combined. With a spatula, fold in the chocolate and nuts. Cover the bowl of cookie dough and place it in the refrigerator for at least 2 hour. Dough can be kept in the fridge over night.
Line 2 baking sheets with parchment paper. Scoop 2 tbsp sized amounts of dough and roll them into a ball. Arrange the dough balls about 2 inches apart on your baking sheet.
Preheat your oven to 350 degrees. Bake until cookies are golden brown on bottom, about 12 to 15 minutes. Let cool on the baking sheets for 10 minutes and then transfer to cooling racks.