How to Make It
Preheat oven to 425ºF. Line an 11-by-17-inch rimmed baking sheet with parchment paper. Coat the parchment and sides of the pan with nonstick cooking spray. Set aside.
Whisk the buttermilk, eggs, vanilla, and 2 tablespoons melted butter in a medium bowl until combined. In a separate large bowl, whisk the flour, sugar, baking powder, baking soda, and salt. Add the milk-egg mixture and stir until just combined (do not overmix).
Scrape the batter into the prepared baking sheet, smoothing into an even layer with a spatula.
Bake until the pancake is lightly golden and springs back in the center when poked, 11 to 13 minutes. Remove from oven and heat the broiler to high. Brush the remaining 2 tablespoons melted butter onto the pancake. Broil until golden brown, 1 to 2 minutes, rotating halfway.
Cut into 12 slices and serve warm.
Mix-In Idea 1: Bananas, Cinnamon, and Chopped Peanuts
Mix 2 teaspoons ground cinnamon into the batter with the dry ingredients, then prepare recipe as written. Scrape batter into the pan and top with 2 sliced bananas. Bake according to recipe, brush with melted butter, and top with 1 tablespoon granulated sugar before broiling. Serve topped with ½ cup chopped salted roasted peanuts.
Mix-In Idea 2: Blueberries, Lemon Zest, and Powdered Sugar
Mix 2 teaspoons lemon zest (from 1 lemon) into the batter with the milk, then prepare recipe as written. Scrape batter into the pan and top with 1 cup fresh or frozen blueberries. Bake then broil according to recipe. Dust with powdered sugar.
Mix-In Idea 3: Raspberries and Cream Cheese Swirl
Whisk ¾ cup (6 ounces) room-temperature cream cheese with ¼ cup milk and 3 tablespoons powdered sugar until completely smooth. Prepare the pancake batter according to recipe and scrape into pan. Dot cream cheese mixture evenly over pancake batter, then use a butter knife or a skewer to make a swirl pattern. Dot with 1½ cups (6 ounces) fresh raspberries. Bake then broil according to recipe.