My Secret to Belgian Waffles are crispy on the Outside

Ingredients

• 1 cup (125g) all-purpose flour, plus more for dusting
• 1 teaspoon (5g) active dry yeast
• 1 tablespoon (12g) granulated sugar
• 1/4 teaspoon (1.5g) salt
• 1 1/4 cups (300ml) lukewarm milk (whole or 2% preferred)
• 1 large egg
• 4 tablespoons (56g) unsalted butter, melted and slightly cooled
• 1 teaspoon vanilla extract
• Vegetable oil or non-stick cooking spray, for waffle iron