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 smooth and fully incorporated.
03 - Gently fold wet mixture into dry ingredients 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 until thoroughly blended and uniform in color. Keep second bowl plain for vanilla batter.
05 - Heat waffle iron according to manufacturer instructions. Lightly grease cooking surface with oil or nonstick cooking spray.
06 - Drop alternating spoonfuls of red velvet and vanilla batters onto center of hot iron. Use chopstick or butter knife to gently swirl batters together for marble effect without completely blending.
07 - Close lid and cook until golden brown, crisp, and cooked through, approximately 3 to 5 minutes per batch.
08 - Serve immediately while warm. Top with cream cheese glaze, maple syrup, or fresh fruit as desired.