Preheat oven to 350 F. In a large bowl, whisk together flour, sugar, cocoa powder, salt, and baking powder. Add in melted butter, eggs, and peppermint extract. Whisk until smooth.
Spread brownie batter into a greased baking dish. Bake for 30-35 minutes. Let cool completely.
Evenly spread softened ice cream over cooled brownie. Top with frozen whipped topping and drizzle with the chocolate syrup. Cover and freeze for at least 4 hours.