In a large mixing bowl, whisk together all-purpose flour, sugar, baking powder, baking soda, and salt until combined. In another bowl, mix buttermilk, eggs, melted butter, and vanilla. Fold wet ingredients into dry to form the classic batter.

In a separate bowl, combine all-purpose flour, cocoa powder, sugar, baking powder, baking soda, and salt. In another bowl, mix buttermilk, egg, melted butter, vanilla, and red food coloring. Combine wet and dry ingredients carefully for red velvet batter.

Preheat the waffle iron according to the manufacturer's instructions and lightly grease it for easy release.

Spoon alternating dollops of classic and red velvet batters onto the waffle iron. Use a toothpick to swirl the batters for a marbled effect.

Cook the waffles according to the manufacturer's guidelines for about 4-5 minutes or until golden brown and crisp.

Remove waffles from the iron and serve warm, topped with whipped cream, fresh berries, or syrup.