Place eggs, flour, milk, sugar, vanilla, and salt into the blender. Blend for a few minutes, scraping down sides if needed, until the batter is fully blended. Allow batter to rest.
Place pan with butter into oven. Allow butter to melt. Remove the pan from oven once butter has melted. Tilt pan to make sure the butter coats entire pan.
Pour the batter into the the pan on top of melted butter. Make sure batter covers the entire pan.
Bake for 425 degrees for 18-20 minutes, until edges are browned and pancake has puffed up. Check on the pancake in closed oven at around 15+ minutes to make sure the pancake is puffing up and not getting too brown.
Notes
If your oven runs a little hotter, reduce temperature to 400 degrees, bake for 20+ minutes.