Preheat oven to 425°F/220°C. Place 3 to 4 tablespoons butter in a 9x13 baking dish, then put the dish into the oven while it preheats to melt the butter. Keep an eye on it so the butter doesn't burn.
Meanwhile, combine the eggs and milk in a blender. Add the flour and salt and blend until just combined and smooth; do not overblend.
Swirl the melted butter over the bottom of the preheated pan, pour the batter in, then immediately return the pan to the oven. Bake for about 20 minutes, until the pancake is puffy and browned on the edges.
Serve warm with syrup, jam, whipped cream, fruit, powdered sugar, or a combination thereof.