Preheat the oven to 425°F (220°C). Place your baking dish or skillet in the oven while it's preheating (this will help the batter puff up).
Make the batter: If you have a high speed blender - just add all the ingredients and blebd until the batter is smooth, about 30 seconds.
If you have a hand/immersion blender or prefer to whisk the batter by hand: first add eggs, flour, sugar, vanilla, and salt to a large bowl. Mix or whisk until smooth. Add the milk and continue mixing until smooth.
When the oven is heated up, take the baking dish out of the oven and add the butter. Melt the butter moving it all around the baking dish, also on the edges, it should melt quickly.
When the butter is melted, pour in the batter.
Place the baking dish again in the oven and bake for about 15 minutes or until golden and puffed up.
Take out of the oven, cut into servings and serve immediately.
Dutch baby pancakes puffs up in the oven but quickly deflates when taken out of the oven, this is normal.
Enjoy!