Preheat oven to 350 degrees
Generously butter (or spray with cooking spray) a 13x9 inch baking pan
In a large mixing bowl, beat the butter until light and fluffy
Add the granulated sugar and beat until incorporated, then add the brown sugar and beat until well mixed in and things are looking light and airy.
Add the eggs, one at a time. After adding the first egg, beat for one minute until adding the second, then beat for an additional minute.
Add the vanilla and let it mix in as well.
Stop the mixer and add the baking soda, salt, and baking powder. Stir or mix slowly to incorporate, then add the flour one cup at a time and mix on low or medium-low until the mixture comes together.
Add the package of semi-sweet chocolate chips and mix until blended.
Add the 1 ½ cups chopped pistachio nuts and continue mixing until blended in with everything else.
Scoop the mixture into your prepared 13.9-inch pan. Take a few minutes with this to make sure your dough is evenly distributed. Sometimes I start with a butter knife, then end up smooshing it around with my hands to make sure all the corners and edges are covered.
Sprinkle the 1 cup dark chocolate chips over the dough.
Sprinkle ½ - ¾ cup chopped pistachios over the dough.
Now, using your hands, just pat all of that topping stuff gently down so it gets a good grasp onto the dough.
Into the oven it goes for right about 40 minutes, or until everything is a nice golden brown and the dough starts to pull away from the side of the pan.
Remove from the oven and cool on a cooling rack until you can’t stand it anymore. Dive in!!
NOTE: If you want, you can line your pan with foil, making sure to run the foil up about 1 inch over the short sides of the pan. This lets you just lift the whole thing out of the pan when cooled and is a lot easier to slice. Up to you – just thought I’d throw it out there to think about.