Preheat oven to 425°
As oven preheats, put the butter in an un-greased 9x13" metal pan and place in oven, until melted
Place the eggs, milk, flour, salt and vanilla in a blender; cover and process until smooth
Pour batter into baking dish, over melted butter
Bake, for 22-27 minutes or until edges are golden brown and puffy
To serve, sprinkle generously with powdered sugar and syrup