Preheat your oven to 350℉. Spray a 9x12-inch pan with nonstick spray. Use a 9x9-inch pan for thicker brownies (will have to bake a bit longer).
In a large bowl, use an electric mixer to combine the sugar and butter. Beat in the eggs. And then beat in the flour and chocolate syrup until well-combined. Stir in the nuts (if using).
Pour the brownie batter into the prepared pan, and bake for 30 minutes (or until the brownies begin to pull away from the sides of the pan). Let cool before cutting.