1 tablespoon melted unsalted butter, plus more for cooking
In a medium bowl, whisk the eggs, 1/2 cup of the milk and the sugar and salt until combined. Whisk in the flour until the batter is smooth. Whisk the remaining 1 cup of milk and the 1 tablespoon of melted butter into the batter. Let the batter stand at room temperature for 1 hour.
Heat a 7-inch crêpe pan over moderate heat and brush with melted butter. Pour 3 tablespoons of the crêpe batter into the pan and immediately rotate the pan to coat the bottom evenly. Cook the crêpe until lightly browned on the bottom, about 30 seconds. Flip the crêpe and cook until brown dots appear on the second side, about 10 seconds longer. Transfer each of the crêpes to a large plate as it is cooked. Continue making crêpes with the remaining batter, adding melted butter as needed, to make 16 to 18 crêpes.