Toast the black sesame seeds for 20-30 seconds. Add black sesame seeds to a food processor or spice grinder. Pulse until it has broken down into a fine powder. Set aside. It is also available pre-ground as sesame powder. Use 3 tablespoons of powder.
Separate egg yolk and egg white.
Add the melted butter, granulated sugar, vanilla extract, salt, egg yolk, and whole milk to a large bowl. Mix until well incorporated.
Add the black sesame seeds, flour, and baking powder to the mixture and mix until well incorporated.
Beat egg white until soft peaks form. Stir a quarter of the white into the batter then fold in the rest. The batter will be loose and very pourable.
Preheat waffle maker. The batter will make 4 Belgian waffles with a bit leftover.
Add about 1/3-1/2 cup of the batter to each square of the waffle iron, because the batter is loose it will fill the square. Cook for 3-5 minutes until brown and crispy. Once there is no more steam coming from the waffle iron, the waffle should be done. The waffles will be darker than normal due to the black sesame. Follow directions for your waffle maker.
Serve with butter, maple syrup, and fresh berries.