Preheat oven to 425 degrees F. Place a 10 inch cast iron skillet into the oven to get hot.
Meanwhile combine the eggs, milk, flour, granulated sugar, vanilla and salt in a blender and blend for 10 seconds. Scrape down sides and blend again until smooth. Let batter rest for at least 15 minutes.
Once the batter has rested carefully remove the hot skillet from the oven and add the butter. Let the butter melt and swirl it around the pan. Quickly pour in the batter and return skillet to the oven. Bake for 15-20 minutes, until golden brown and puffed.
Remove from oven and dust with powdered sugar and top with desired toppings. Cut into slices and enjoy!