Combine milk, eggs, butter, flour, sugar, and salt in a blender and blend until smooth. Refrigerate the batter for 1 hour.
When you’re ready to make the crêpes, blend the mixture once more.
Heat a small nonstick skillet over medium-high heat. Using a ¼-cup measuring cup, pour 1/4 cup of the batter into the skillet and immediately tilt the skillet so that the batter coats the entire bottom of the pan. Cook until the crêpe starts to bubble on top and is golden brown on the bottom, about 1 minute. Flip the crêpe and cook for 30 more seconds. Transfer to a plate and repeat the process with the remaining batter.