Start by separating the egg yolks and egg whites into two different bowls. This step helps in achieving a lighter and fluffier waffle.

In a large bowl, whisk together the flour, brown sugar, vanilla sugar, orange zest, baking powder, and salt. Make sure they are well combined.

In the bowl with the egg yolks, add the milk and whisk them together until smooth.

Gradually add the wet ingredients (egg yolk and milk mixture) to the dry ingredients, mixing until just combined. Be careful not to overmix, a few lumps are fine.

In the separate bowl, use a clean whisk or electric mixer to beat the egg whites until stiff peaks form. This will add airiness to your waffles.

Gently fold the beaten egg whites into the waffle batter. Do this in two additions to maintain the airiness. Your batter should be thicker than pancake batter.

Preheat your waffle maker according to the manufacturer's instructions. Once hot, lightly brush the plates with some melted butter to prevent sticking.

Pour about 1/2 to 3/4 cup of batter onto the hot waffle maker, depending on its size. Close the lid.

Cook for 3-5 minutes, or until the waffles are golden brown and crispy, and steam stops escaping from the sides. Cooking time may vary based on your waffle maker.

Carefully remove the cooked waffle and place it on a wire rack to prevent it from becoming soggy while you cook the remaining batter.

Serve the waffles warm! They are delicious on their own or with your favorite toppings like fresh fruits, melted chocolate, a dollop of jam, maple syrup, or whipped cream. Enjoy!