Step 1

Place an oven rack in the middle position and preheat the oven to 450°F. Place a 9- or 10-inch cast iron skillet over low heat on your stovetop. Keep it over low heat while you prepare the batter.

Step 2

Melt two tablespoons of the butter in a small skillet, then transfer to a blender. Add the milk, flour, eggs, granulated sugar, vanilla, salt, and lemon zest, and blend until smooth. (Do not skip this step — the batter will be lumpy if you do.)

Step 3

Place the remaining 2 tablespoons of butter into the cast iron skillet. Turn the heat up to medium-high. Let the butter melt, add the blueberries, and give the skillet a shake. Immediately pour the batter over the blueberries and transfer the skillet to the oven. Bake until the pancake is puffed and golden, about 15 minutes.

Step 4

Remove pan from the oven, and dust with confectioners sugar, if you wish. Cut and serve immediately with maple syrup.