Prepare pizza pan by spraying with non-stick spray and lining bottom with parchment paper.
In a large bowl mix up the brownie batter following instructions on the box of brownie mix.
Pour the batter into the pizza pan and use a spoon to spread it out until it is level.
Bake according to box instructions for a 13x9 inch brownie pan.
Once it is finished baking remove it from the oven and let it cool completely.
When cooled and ready for the "sauce" place 1 cup of Nutella in a microwave-safe bowl and microwave for 15 -30 seconds until it is slightly runny. Spread over the brownie layer leaving a 1-inch edge around the outside of the brownie.
Sprinkle on the Halloween candy.
Cut and serve. If not serving immediately you can refrigerate this until ready to serve.