Preheat oven to 325°F and spray a 9x12 Glass Baking Dish with nonstick pan spray
In a small bowl, combine melted butter and graham cracker crumbs to make the crust. Once combined, press the crust down in your baking dish.
In a large bowl, mix together softened butter and sugar. Add in eggs and vanilla. Stir until combined
In a separate bowl, mix the baking powder, salt, and flour. Mix flour mixture into the butter mixture. until combined. Fold in the chocolate chips and marshmallows
Once the dough is ready, spread it on top of the crust with a spatula. Scatter the broken candy bar pieces, graham cracker pieces, and marshmallows on top of the dough.
Bake for approx 30 to 35 minutes, or until lightly browned. Test with a tooth pick. Allow to cool before serving.