In a small bowl, whisk the brown sugar and yeast into the lukewarm milk 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 1 at a time, mixing for 20 seconds between each. Whisk the vanilla with the 12 tablespoons 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 thebatter rise in a warm place until doubled in size, about 1 hour.

Stir the pearl sugar into the risen batter. Cover again and let rest for 15 minutes. Divide dough into 4-ounce balls. You should have 16 dough balls.

Preheat waffle iron for 10 minutes. Grease the iron generously before each waffle.

Cook 1 piece of dough at a time. Place the dough in the middle of the iron, close and cook until the outside is crisp and the center is cooked through. This time will vary depending on the heat level of your waffle maker.