Preheat the oven to 350°F and grease a 9x13 inch baking dish with butter or nonstick cooking spray.
In a large mixing bowl, cream together the softened butter, brown sugar, and granulated sugar using an electric hand mixer.
Once the butter and sugars are fully combined, add the eggs and mix again on a high speed until the eggs are well incorporated.
Maintaining a high speed on the hand mixer, add the baking powder, baking soda, and flour to the mixing bowl. Mix for about 1 ½ - 2 minutes, or the ingredients are fully combined.
Use a large spoon or spatula to gently fold in the chocolate chips, ensuring they are evenly distributed throughout the cookie dough.
Press half of the cookie dough into the bottom of the baking dish and top it with the marshmallow fluff. Use a spatula to spread the marshmallow fluff evenly to the edges of the pan
Layer the graham crackers evenly over the marshmallow fluff and top with the remaining cookie dough. Bake your bars for 20-25 minutes, or until a toothpick can be cleanly removed from the center of the pan.
Allow the bars to cool on the counter for an hour before slicing. Serve and enjoy!