Delicious Japanese pancakes

Ingredients for delicious Japanese pancakes:

• Nonstick cooking spray, for the skillets
• 3 cups cake flour
• 6 tablespoons confectioners’ sugar
• 1 teaspoon pure vanilla extract
• 1 teaspoon kosher salt
• 2 large eggs, separated, plus 4 whites
• 2 1/4 cups milk
• 1 stick (8 tablespoons) unsalted butter, melted and cooled, plus more for serving
• 4 teaspoons baking powder
• 1/2 teaspoon cream of tartar
• Maple syrup, for serving
• Whipped cream, for serving
• Assorted fresh berries, for serving.

Preparation form delicious Japanese pancakes:

Position oven racks in the top and bottom thirds of the oven and preheat to 450 degrees F. Lightly spray one small (8-inch) and one medium (10-inch) ovenproof nonstick skillet with nonstick cooking spray (or brush lightly with melted butter).
Whisk together the sugar, flour, baking powder and salt. Whisk together the vanilla, milk, melted butter, and egg yolks until combined.  
Beat the egg whites and cream of tartar in a second large bowl with an electric mixer on medium-high speed until stiff peaks form.
Stir the milk mixture into the flour mixture until just combined (it’s okay if there are a few lumps). Stir one-third of the egg white mixture into the flour-milk mixture. Then gently fold in the remaining egg whites until just combined (take care not to overmix).  
Pour 3 cups of the batter into the small skillet and pour the remaining batter into the medium skillet. Cover each skillet with a lid (or cover and seal with aluminum foil). Bake, rotating the top of the skillet to bottom halfway through until the pancakes are cooked through and the bottoms are golden, 15 to 17 minutes. 
Flip the larger pancake onto a serving platter and top with the smaller pancake. Pour a generous amount of syrup over the stack and top with whipped cream and berries. Serve with butter on the side.