Cream together 1 cup softened butter, ¾ cup brown sugar and ¾ sugar and 1 teaspoon vanilla extract using a stand mixer or hand mixer for 3-5 minutes. The butter should be lightened in color and appear fluffy, but you'll still be able to feel the granules of sugar when you rub the mixture between your fingers.

Add in two eggs and egg yolk, one at a time. Add 2 ¼ cups flour (gradually, if you prefer), 1 teaspoon baking soda and 1 teaspoon salt, until just combined.

Gently stir in chocolate chips and walnuts.

Use a cookie scoop (or two spoons) to drop 1 tablespoon sized cookie dough balls onto cookie sheets (lined with parchment paper if not non-stick). Bake chocolate chip cookies for 10-11 minutes until edges are golden brown but centers are still soft. They will continue cooking as they cool on the baking sheet and wire cooling rack.

Repeat scooping and baking process for remaining cookies or freeze cookie dough for later (see below for instructions on how to freeze cookie dough).

Cool your gooey chocolate chip cookies on the baking sheet for 3 minutes then transfer them to a wire cooling rack to continue cooling completely.

Store your chocolate chip cookies in an airtight container or ziptop bag.