Heat waffle iron until it’s piping hot!
Separate egg whites and yolks in two bowls, and set aside.
Warm the milk and combine with yeast and sugar. Allow to bloom for 10 min.
Meanwhile, melt the butter in a small sauce pan and beat the egg whites into stiff peaks.
Lightly beat yolks and add warmed milk mixture; beat until incorporated. Add the sparkling water and stir gently until well-combined.
Sift flour directly into the milk mixture and add a pinch of salt; beat with an electric mixer until all lumps are smoothed out.
Pour the melted butter into batter and gently fold in stiffened egg whites by hand. Set batter aside for 20-30 minutes, so yeast can work and batter has time to rise.
When the batter shows bubbles, you’re ready to start baking!
Butter or oil all sides of your waffle iron, even if it is non-stick. Pour ⅓ cup of batter per waffle, and allow waffle to brown completely.
Serve with powdered sugar, brown sugar or whipped cream for an authentic Belgian treat!