01 - Sift together flour, sugar, baking powder, baking soda, and salt in a large mixing bowl.
02 - Whisk buttermilk, eggs, melted butter, and vanilla extract in a separate bowl until smooth and fully incorporated.
03 - Pour wet mixture into dry ingredients and fold gently until just combined. Avoid overmixing to prevent tough waffles.
04 - Divide batter evenly between two bowls. Add cocoa powder and red food coloring to one bowl; stir thoroughly until uniform color achieves deep red hue.
05 - Heat waffle iron according to manufacturer guidelines. Lightly coat cooking surfaces with oil or nonstick cooking spray.
06 - Spoon alternating mounds of red velvet and vanilla batters onto center of hot iron. Drag chopstick or butter knife through batters in swirling motion to create marbled effect.
07 - Close lid and cook until waffles reach golden brown color with crisp texture, approximately 3 to 5 minutes per batch.
08 - Transfer waffles to serving plates and serve immediately with cream cheese glaze, maple syrup, or fresh berries.