Whisk flour, 1½ tablespoons granulated sugar, yeast, and salt together in bowl of stand mixer. Add butter, milk, egg, and vanilla. Fit stand mixer with dough hook and mix on low speed until all flour is moistened, about 1 minute. Increase speed to medium-low and continue to mix until dough is smooth and elastic, 12 to 15 minutes, scraping down bowl halfway through mixing (dough will be very soft and will stick to sides and bottom of bowl). Transfer to medium bowl. Cover and refrigerate for at least 8 hours or up to 48 hours.

Line rimmed baking sheet with parchment paper and spray lightly with vegetable oil spray. Transfer dough to counter and flatten to about 1 inch thickness (dough will be firm). Spread pearl sugar over dough and press into dough. Beginning with edge nearest you, roll dough into cylinder, enclosing sugar. Knead dough until sugar is evenly incorporated (a bench scraper is helpful for releasing dough from counter; if pieces of sugar pop out of dough, press them back in).

Divide dough into 8 equal portions (each should weigh just over 3½ ounces or 99 grams). Roll 1 portion between your hands to form 4-inch-long sausage shape. Pat into rough 4 by 2-inch oval. Transfer to prepared baking sheet. Repeat with remaining portions. Cover and let rise until puffy and room temperature, 1½ to 2 hours.

Heat Belgian waffle iron to 360 degrees (drop of water on iron will skitter across surface and take 4 to 5 seconds to evaporate). As iron heats, spread remaining ⅓ cup granulated sugar in small dish. Place 1 dough portion in sugar and turn to coat on all sides. Transfer to center of waffle iron and close lid so it rests on dough but do not press down or lock. Cook until waffle is deep golden brown and surface sugar is beginning to caramelize, about 2½ minutes. Using 2 forks, spear waffle on left and right sides; lift, and transfer to wire rack to cool (surface sugar will be hot; do not handle for at least 90 seconds). Repeat with remaining dough and serve.