Preheat the Oven and Skillet: Heat your oven to 400°F (200°C). Place the butter in a 6.5-inch cast iron skillet (or a 5x5-inch baking dish) and put it in the oven to preheat.
Make the Batter: In a bowl, whisk together the egg, milk, vanilla extract, and sugar. Once mixed, whisk in flour and a pinch of salt until smooth.
Assemble and Bake: Carefully remove the hot skillet from the oven and swirl the melted butter to coat the bottom and sides. Add the blueberries, then pour the batter over the top. Bake for 20-25 minutes, until puffed and golden brown.
Serve and Enjoy: Carefully lift the Dutch Baby out of the skillet with a spatula and place it on a plate or cooling rack. Let it cool slightly, then dust with confectioners’ sugar and top with more berries if desired.
Notes
Smooth Batter Matters: Whisk until the batter is smooth with minimal lumps. A whisk or hand mixer works best.
Preheat the Skillet: A hot pan is key for a good rise. Preheating helps the Dutch Baby puff up properly.