Preheat a waffle iron. If you plan to keep the waffles warm until serving time, pre-heat the oven to 200°F (93°C).
In a large mixing bowl, stir together flour, sugar, baking powder and salt. In a medium bowl, whisk together the milk, orange juice, egg yolks and orange zest. In a third bowl, whisk together the egg whites until frothy and firm, but not quite stiff.
Make a well in the dry ingredients and slowly pour in the milk mixture. Gently mix until just combined. Add the melted butter in a slow, steady stream and stir until incorporated. Gently fold in the egg whites.
Grease waffle iron. Pour in ½ cup of batter (more or less, depending on your waffle iron). Cook approximately 3 minutes or until crisp and golden brown. If not serving immediately, place on a baking sheet in a single layer and keep in the warm oven.
Vanilla Bean Butter
In a medium bowl, mix together butter, brown sugar, vanilla seeds, cinnamon and salt. Set aside until ready to serve. If making in advance, store in a small bowl wrapped in plastic wrap. Return to room temperature before using.