01 - Whisk together flour, sugar, baking powder, baking soda, and salt in a large bowl until well incorporated.
02 - In a separate bowl, whisk buttermilk, eggs, melted butter, and vanilla extract until completely smooth.
03 - Gently fold the wet mixture into the dry ingredients, mixing just until combined. Avoid overmixing to maintain tender texture.
04 - Divide batter evenly between two bowls. Add cocoa powder and red food coloring to one bowl; stir thoroughly until fully incorporated and evenly colored. Leave the second bowl as plain vanilla batter.
05 - Heat waffle iron according to manufacturer instructions. Lightly coat cooking surface with oil or nonstick cooking spray.
06 - Drop alternating spoonfuls of red velvet and vanilla batters onto the center of the hot iron. Gently swirl with a chopstick or butter knife to create marbled pattern.
07 - Close lid and cook until waffles are golden brown, crisp on the outside, and completely cooked through, approximately 3-5 minutes per batch.
08 - Serve immediately while warm. Accompany with cream cheese glaze, maple syrup, or fresh berries as desired.