How to Make It
In a small bowl, whisk the brown sugar and yeast into the lukewarm water and let stand until foamy, about 5 minutes. In the bowl of a standing mixer fitted with the paddle, mix the flour with the salt. Make a well in the center of the bowl and pour in the yeast mixture. Mix at medium speed until shaggy, about 1 minute. Add the eggs one at a time, mixing for 20 seconds between each. Whisk the vanilla with the 1 cup of melted butter. With the mixer at medium-low, gradually mix in the butter until smooth; the batter will be thick and very sticky. Cover the bowl with plastic wrap and let the batter rise in a warm place until doubled in size, about 1 hour and 45 minutes.
Stir the pearl sugar into the risen batter. Cover again and let rest for 15 minutes.
Preheat the oven to 250°. Preheat a Belgian waffle iron and brush it with melted butter. Gently stir the batter to deflate. Using about 2 tablespoons of batter for each, cook the waffles according to the manufacture's directions until they are golden and crisp; brush the waffle iron with melted butter as needed. Transfer the waffles to plates or keep them warm in the oven, then serve.
The batter can be prepared through Step 1 and refrigerated overnight.
Belgian pearl sugar is available at specialty shops and at amazon.com.