Preheat the oven to 425 degrees F (220 degrees C).
Place butter in a 9-inch pie dish. Place in the preheating oven until butter is melted, 5 to 10 minutes.
Meanwhile, whisk together flour, milk, eggs, white sugar, and salt in a bowl. Pour mixture into butter in dish.
Bake in the preheated oven until the edges are light brown, and a toothpick inserted into the center comes out clean, 20 to 24 minutes.
Sprinkle lemon juice over pancake and dust with confectioners' sugar. Serve warm.
