If you live at high altitude see baking notes below for adjustments! *
Preheat oven to 375°F and spray a 9x13* cake pan or dish with non-stick spray
In a mixer or with a hand mixer and the paddle attachment, mix together the butter, white sugar, brown sugar, and vanilla. (1 cup butter, ¾ cup white sugar, 1 ½ cups brown sugar, 1 teaspoon vanilla)
Add in each egg, on at a time. Mix in each egg completely before adding the next. The mixture should get lighter in color and thicker.
In a small bowl mix together the flour, salt, baking soda, instant pudding, graham crackers. (2 ¼ cups flour, 1 teaspoon salt, 1 teaspoon baking soda, 1 box instant pudding mix, 1 ½ cup crushed graham crackers)
Add flour mixture to the butter mixture and mix on medium high until fully incorporated.
Stir in by hand the chocolate chips, part of the mini marshmallow, the chopped Hershey Bars. (1 ½ cups milk chocolate chips, 2 ½ cups mini marshmallows, 3 chopped Hershey candy bars)
Place dough into the prepared baking dish* and bake for 20-25 minutes. You want the edges to look a little brown and the center baked through.
Allow to cool and enjoy!