Step 1

Place a rack in the center of your oven. Set a 9x13-inch baking dish on the rack, then preheat the oven (with the dish in it) to 425 degrees F.

Step 2

In a stand mixer fitted with the whisk attachment or a medium mixing bowl with a hand mixer (or by hand with some elbow grease), briskly combine the eggs, milk, vanilla, and lemon zest. Add the all purpose flour, whole wheat pastry flour, sugar, and salt. Continue whisking until the batter is very smooth and no lumps remain. If you need to do so, melt the butter and have it on hand. Keep a pastry brush or similar on hand as well.

Step 3

When the oven has preheated, remove the baking pan from the oven and immediately pour in the melted butter. Be careful, as the butter will splatter and sizzle when it hits the hot pan. With a pastry brush, quickly spread the butter up the sides of the pan, then pour in the batter. Sprinkle the top with 1/2 cup blueberries.

Step 4

Bake the pancake for 20-25 minutes, very puffy, deep golden brown on the top edges, and the center has set. Check the pancake at the 15-minute mark. If it has already begun to turn very brown on top, place a sheet of aluminum foil loosely over the the top to shield it, then continue baking as directed. Dust with powdered sugar. Slice and serve warm with desired toppings.