1. Add the flour, milk, eggs, sugar, vanilla, and salt in a blender or food processor. Blend for 20 seconds, scraping down the sides. The batter should be quite liquid.

2. Keep the batter in the blender and set aside to rest 20 to 25 minutes. This step is optional but generally makes for a tastier batter.

3. In the meantime, preheat your oven to 425°F (210°C) and place a cast iron skillet on the middle rack to warm along with the oven.

4. When ready to make the Dutch baby, remove the skillet from the oven (use oven mitts) and place it on top of your stove. Add butter the skillet and give a good swirl to melt the butter and coat the bottom and sides.

5. Once the bottom of the skillet is covered in butter, pour the batter into the skillet. Tilt the pan if needed so that the batter runs evenly to all sides. Transfer the cast iron skillet to the oven.

6. Bake until the Dutch baby pancake is puffed and golden-brown on top; count approx. 15 to 20 minutes.