Prepare the Batter. In a large bowl, whisk together the flour, milk, eggs, melted butter, sugar, and salt until the batter is smooth and free of lumps. The batter should be thin and pourable.
Preheat the Pan. Heat a non-stick skillet or crepe pan over medium heat. Add a small amount of butter to coat the pan.
Cook the Pancakes. Pour a small amount of batter into the pan, just enough to thinly cover the bottom (about 1/4 cup). Swirl the pan to spread the batter evenly. Cook for 1-2 minutes, or until the edges begin to crisp and the bottom is lightly golden. Flip and cook for an additional 30 seconds.
Transfer to a Plate. Place the finished pancake on a plate and repeat with the remaining batter, adding more butter to the pan as needed.
Serve Warm. Swedish Pancakes are best served fresh, topped with your favorite fillings.