In a blender, combine the melted butter, flour, sugar, salt, milk, water, eggs, and vanilla extract, if using. Put the lid on tightly and blend for 20 seconds or until well combined and smooth. The consistency should be similar to heavy cream. Chill the crepe batter, covered tightly, in the refrigerator for at least 1 hour. It will keep for up to 48 hours.
When you are ready to cook the crepes, remove the batter from the refrigerator. Give the batter a quick whisk. Heat a 10-inch non-stick skillet over medium heat and lightly coat the pan with butter.
Pour a 1/4 cup of batter into the center of the hot pan, tilting and swirling the pan until batter evenly coats bottom. The batter is supposed to be thin. Cook until the bottom is set and lightly golden brown, about 1 minute.
Lift one edge of crepe with an offset spatula, then use your fingers to gently flip crepe. Cook on second side until just set and speckled with brown spots, about 45 seconds.
Transfer the cooked crepe to a large plate, making sure it is laid out flat. Continue cooking crepes until the batter is gone, making sure you add more butter to the pan, so the crepes don’t stick.
Serve the crepes with desired fillings and toppings. You can roll or fold the crepes into fourths, creating a triangle or fill with desired fillings then fold. Some of our favorites include whipped cream, berries, confectioner’s sugar, Nutella, banana slices, jam, lemon curd, and cinnamon sugar. See the post for more suggestions.