In a blender, combine the flour, sugar, salt, milk, eggs, and butter. If you don't have a blender, mix everything together using a whisk. Purée until the mixture is smooth and bubbles form on top, about 30 seconds.
Heat a 12-inch (30 cm) nonstick skillet or pan over medium heat. Lightly coat it with butter. Add 1/3 cup of batter and swirl it to completely cover the bottom of the skillet; the crepe should be about 8 inches (20 cm) in diameter.
Cook until the underside of the crepe is golden brown and the edges are crispy, about 2 to 3 minutes.
Loosen the edge of the crepe with a rubber spatula and quickly flip it over. Cook for 1 minute. Slide the crepe out of the skillet and repeat with the remaining batter, coating the pan with butter as needed.
Fold the crepes over and serve immediately with powdered sugar, maple syrup, Nutella, or chocolate sauce. Add berries of your choice, if desired.