Preheat the oven to 425°F.
Add all ingredients, except for the butter, to a blender and blend until smooth; about 15 seconds.
Allow the batter to sit for 10 minutes if time allows.
Place a 9” or 10” oven-safe cast iron skillet in the oven.
Carefully, remove the pan from the oven and add the butter and swirl around until it coats the pan.
Pour the batter into the pan. Tilt the pan to evenly distribute the batter, if needed.
Bake until the dutch baby is puffed and golden, about 15-20 minutes.
Serve with confectioners sugar, berries and maple syrup!