Preheat the oven to 350 degrees Fahrenheit and lightly spray a 9"x13" pan with nonstick baking spray.

In the bowl of an electric mixer, cream together softened butter, brown sugar, eggs and vanilla.

In a separate bowl, whisk together flour, baking powder, and salt.

Add flour mixture to the wet mixture and mix just until incorporated, scraping down the sides in between.

Stir in nuts and chocolate chips.

Spread evenly in prepared pan.

Bake for approximately 23-25 minutes. Be very careful not to over bake or they'll lose their chewy texture. Set the timer for about 18 minutes at first and then keep checking them every few minutes to avoid over baking. They're done when they're barely set up and not jiggly in the center. You don't want too much browning to happen. They'll continue to set up after being removed from the oven, so plan accordingly.

Let them cool and set up completely, then slice and enjoy!