In a blender, combine the flour, eggs, milk, salt, and 2 tablespoons of the melted butter. Blend until smooth with no lumps, 20 to 30 seconds.
In a 10-inch cast iron skillet, heat the remaining 2 tablespoons melted butter over high heat until foamy. Add the batter and immediately put the skillet in the oven. Bake until the outside of the pancake is puffed and a deep golden color, 17 to 18 minutes.
Remove from the oven, slather with softened butter, and cut into quarters. Pour syrup over the pancake slices and dust with powdered sugar.
Notes
If you don't have a cast iron skillet, you can use a heavy ovenproof skillet.Nutritional values are based on one serving