Place a 10-inch cast iron skillet on the center rack of the oven and preheat to 425°F (220°C).
Combine eggs, flour, milk, sugar, vanilla, and salt in a blender.
Process on high for 45 seconds until the batter is completely smooth and aerated.
Remove the hot skillet from the oven and add the butter, swirling it until fully melted and coating the bottom and sides.
Pour the batter immediately into the center of the hot skillet.
Return the skillet to the oven and bake for 15 to 20 minutes until the pancake is puffed and the edges are dark golden brown.
Avoid opening the oven door during the baking process to prevent the structure from collapsing.
Remove from the oven and serve immediately while puffed, topped with powdered sugar and lemon juice.