Preheat your oven to 350°F (175°C) and prepare a baking pan.
Melt the butter in a saucepan over medium heat.
Remove from heat and stir in the sugar until well combined.
Add in the eggs one at a time, whisking after each addition.
Mix in the vanilla extract and salt, then fold in the cocoa and flour.
Fold in the leftover Halloween candy, saving some for topping if desired.
Pour the batter into the prepared pan and smooth the top.
Bake for 25-30 minutes, or until a toothpick comes out with a few moist crumbs.
Let the brownies cool in the pan for at least 20 minutes before slicing.
