Preheat the oven to 350°F and grease a 9×13 inch pan. Set aside.
In a microwave-safe bowl, combine the butter and chocolate. Melt in 30 second increments, whisking after each, until completely smooth. Add in the sugars, then whisk in the eggs and vanilla.
Add the salt, flour, and cocoa powder to the bowl. Fold it all together with a rubber spatula or wooden spoon.
Spread half the batter in the pan, then line the peppermint bark across the dish. Pour the rest of the batter on top, spread evenly, and sprinkle some festive sprinkles on top.
Bake for 30 minutes, then test the brownies with a toothpick or plastic knife. Bake in 2 minute increments if not done after 30 minutes.
Let the brownies cool, then cut with plastic knife to prevent crumbling. Enjoy!