Preheat the oven to 400 degrees F (200 degrees C). Place butter in an ovenproof pan or cast iron skillet and place in the oven.

Meanwhile, combine eggs and milk in a bowl. Add flour, sugar, vanilla extract, and salt and whisk for 1 minute to remove lumps.

Remove hot pan from oven and swirl melted butter to coat. Pour batter into the hot pan and return it to the oven.

Bake in the preheated oven until the pancake is puffed in the center and golden brown on the edges, 20 to 25 minutes.

Dust with confectioners' sugar and slice into 8 wedges.