Step 1

Preheat oven to 400°F and set an oven rack in the middle position. Put a 10-inch cast iron skillet or oven-safe nonstick pan into the oven and heat for at least 5 minutes.

Step 2

In a blender, combine the eggs, flour, milk, 1 tablespoon maple syrup, the salt, and vanilla. Blend until completely smooth, scraping down the sides of the blender jar as necessary, about 30 seconds.

Step 3

Open the oven door and drop the butter into the preheated skillet. Close the oven and allow the butter to melt, about 2 minutes (do not let it burn). Carefully remove the hot skillet from the oven and place an oven mitt or dishtowel over the handle to remind yourself that it's hot. Pour the batter into the buttered skillet and carefully place the skillet back into the oven. Bake for about 20 minutes, until puffed and golden. Carefully remove the skillet from the oven (again, place an oven mitt or dishtowel over the handle to remind yourself that it's hot). Dust with confectioners' sugar and top with berries, if desired, then cut into wedges and serve with maple syrup.