01 - Whisk together flour, sugar, baking powder, baking soda, and salt in a large bowl until evenly distributed.
02 - In a separate bowl, whisk buttermilk, eggs, melted butter, and vanilla extract until completely smooth and incorporated.
03 - Gently fold wet ingredients into dry mixture just until 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 to create red velvet batter. Keep remaining batter as vanilla base.
05 - Heat waffle iron according to manufacturer instructions and lightly grease with oil or nonstick cooking spray.
06 - Spoon alternating dollops of red velvet and vanilla batters onto center of hot iron. Use chopstick or butter knife to gently swirl for marbled pattern. Close lid and cook 3-5 minutes until golden and crisp.
07 - Serve immediately with cream cheese glaze, maple syrup, or fresh fruit.