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 vanilla extract, whisk until smooth.
Pour brownie batter into a greased baking dish. Bake for 30-35 minutes. Let cool completely. Evenly spread softened ice cream over brownie. Top evenly with Oreo cookies. Spread whipped cream on top. Drizzle with chocolate syrup. Cover and freeze for at least 4 hours.