1 Preheat cast iron skillet: Preheat oven to 400°F. Put a 10-inch cast iron skillet into the oven and heat for at least 8 minutes.
2 Melt butter: Melt 3 tablespoons of butter in a saucepan or in a microwave. Of the 3 tablespoons, one tablespoon will be for the batter and two for the pan.
3 Make batter: In a blender, put the eggs, egg white, milk, 1 tablespoon of the melted butter, sugar, flour, vanilla, cinnamon, and salt.
Blend until you have a smooth, creamy batter. This should take about 30 seconds.
Be sure to scrape down the sides of the blender carafe with a rubber spatula if necessary.
4 Pour butter, then batter into hot skillet: Carefully remove the very hot skillet from the oven. (Watch out, the handle is HOT! Make sure to use a thick pot holder so you don’t burn your hands.)
Pour the remaining 2 tablespoons of melted butter in the pan and swirl to coat the bottom of the pan.
Gently pour the batter into the hot skillet, making sure not to splatter batter all over the sides of the pan.
5 Bake: Carefully return the pan to the oven and bake for 20 minutes. The Dutch baby will puff up around the edges, even to the point that the sides will obscure the center.
It’s a wondrous sight to behold when watching through the oven window! Do not open the door to peek, though, as opening the oven door even a crack while baking may cause your Dutch baby to fall.
6 Remove from pan and cut into wedges: Once the Dutch baby is done baking, remove the skillet from the oven (again, take care, the handle is HOT) and use a thin spatula to gently coax the pancake onto a large plate. It may fall slightly once removed from the heat, which is totally normal.
To serve, cut into wedges and sprinkle with powdered sugar (and more cinnamon if you wish) and a splash of lemon juice. Great topped with berries or fruit!