• Preheat the oven to 350 degrees.
• Prepare a 9″x13″ baking dish with parchment paper and spray with nonstick cooking spray.
• Note: You’ll want to leave an inch or two of parchment paper over the edge on each end so that you can lift the brownies out of the pan later on.
• In a large mixing bowl mix melted butter, sugar, and brown sugar. Mix until creamed and smooth. This can be done by hand (with a Danish dough hook) or with an electric mixer on low speed until just combined.
• Add eggs and vanilla. Mix.
• Add flour, cocoa powder, and salt. Mix.
• Pour brownie batter into the prepared baking dish. Spread with a rubber spatula.
• Bake brownies for 23-25 minutes. Brownies may seem undercooked, but that is fine. They will continue to bake in the pan while it cools.
• Let brownies cool for 30 minutes (they might still be warm, and that's fine). While they sit, make the ganache.

  Combine ganache ingredients and melt on the stovetop over medium-low heat OR in the microwave in 15-20 second intervals, stirring in between each interval until melted and smooth.
• Pour ganache over brownies and spread until smooth. Let brownies sit for 1 hour at room temperature, then chill for 1 hour in the refrigerator.  The glaze should be set enough to slice, but soft enough to still press the decorations into it. 
• Lift the brownies from the pan, using the parchment paper, and set them on a cutting board. Use a sharp knife to trim the edges and slice them into 20 squares.

HOW TO DECORATE BAT BROWNIES

• Separate Oreo cookies, scraping out the filling. Cut each cookie in half using a sharp knife.
• Press 2 candy eyes and 2 Oreo wings into each brownie.