Preheat oven to 400°F. Coat a 15x10-inch baking pan with nonstick spray. Line bottom of pan with parchment paper.

In a medium bowl whisk together flours, baking powder, 2 tsp. of the cinnamon, and the salt.

In a large bowl whisk together eggs, milk, 1/4 cup melted butter, 1/4 cup maple syrup, and the vanilla. Core and shred 2 apples on the large holes of a box grater (measure 2 cups shredded apple). Stir shredded apple into milk mixture.

Stir flour mixture into milk mixture just until combined. Pour batter into prepared baking pan and spread into an even layer.

Core and thinly slice remaining 2 apples and arrange on top of batter. Lightly brush apple slices with remaining 1 Tbsp. melted butter. Mix sugar with remaining 1/4 tsp. cinnamon. Sprinkle mixture evenly over apples.

Bake 25 minutes or until edges are golden brown and a toothpick inserted into the center of the pancake comes out clean. Let cool 10 minutes. Cut into 12 squares and drizzle with additional maple syrup.