If you haven't melted your butter already, do that now and let it cool.

Pre-heat oven to 350 degrees F.

Line 2 large baking sheets with parchment, spray the parchment with cooking spray and set aside.

In a medium-sized bowl, combine the flour, baking soda and salt and set aside.

In a separate large bowl, whisk the melted butter, egg, granulated sugar and brown sugar together until smooth. Add the vanilla extract, milk and continue to whisk until combined.

Fold in the flour, baking soda, and salt mixture using a rubber spoon or spatula until the dough is an even consistency and there are no visible streaks of flour.

Fold in the chocolate chips and walnuts (nuts are optional!).

Spoon the dough onto the parchment lined baking sheets using a teaspoon or cookie scoop. You want to create two rows of 3 (6 cookies per sheet). Make sure to leave enough space between the cookies to allow for spread.

Place each baking sheet in the oven and bake for 13-15 minutes. Cookies should be golden-brown, and edges will be slightly darker and crispy.

Let the cookies cool on the baking sheets for about 5 minutes. Transfer them to a wire rack to let them finish cooling.