Preheat the oven to 350ºF and line cookie sheets with parchment paper.
If using toasted walnuts, add them to a skillet in a single layer and toast over medium heat for about 3 to 4 minutes. Stir occasionally and remove from the heat.
Either in the microwave or on the stove melt the butter and then set aside.
Combine the all-purpose flour, baking powder, and salt together in a bowl.
Transfer the melted butter to a large bowl and mix in the brown sugar and granulated sugar.
Add in the vanilla extract as well as the two eggs. Beat until just combined.
Slowly mix the dry ingredients into the wet ingredients and mix until a soft dough forms.
Stir the chocolate chips and chopped walnuts into the cookie dough.
Using a #20 cookie scoop (or by three tablespoons) scoop the dough and roll it into a ball.
Press extra chocolate chips and walnuts into the cookie balls and place them onto the prepared cookie sheet.
Bake for 9-11 minutes or until the tops of the cookies is golden.
Allow the cookies to cool for 10 minutes before transferring them to a wire rack to cool completely.
Notes
These cookies can be frozen for up to 3 months and will last 2 to 4 days at room temperature.