Preheat and lightly grease the waffle iron according to manufacturer instructions.
In a bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt.
In another bowl, whisk the eggs, buttermilk, melted butter, and vanilla extract until combined.
Pour the wet ingredients into the dry ingredients and stir gently until just mixed.
Remove about 1 cup of batter and stir in the red food coloring to create the red velvet batter.
Spoon alternating amounts of vanilla and red batters onto the waffle iron and swirl gently with a toothpick to marble.
Cook the waffles for 3 to 5 minutes until crisp and cooked through.
Serve the waffles warm with powdered sugar, cream cheese glaze, or fresh strawberries.