Maple Muffins

Bahan-bahan (12 porsi)

• 2¼ cups all purpose flour, (spooned into measuring cup and leveled-off)
• ¾ cup whole wheat flour, (spooned into measuring cup and leveled-off)
• 1 tablespoon baking powder
• ½ teaspoon salt
• 1½ cups pure maple syrup, (preferably Grade B (Grade A works fine too))
• 12 tablespoons (1½ sticks) unsalted butter, melted and cooled slightly, plus more for greasing the muffin tin
• ½ cup whole milk
• 1 large egg
• 1 large egg yolk
• 1 cup coarsely chopped walnuts, (toasted if desired, optional)