In a medium bowl, whisk eggs, then whisk in milk and melted butter.

In another medium bowl, sift together flour, baking powder, and salt. Add to the egg-milk mixture. Quickly whisk together, ignoring small lumps.

Cover and refrigerate 3 to 6 hours. Stir to recombine, and strain out lumps, if desired (all but the largest lumps will disappear during cooking).

Place a 5-inch skillet over medium heat. When hot, lightly smear with oil.

Pour about 1/8 cup of batter into the pan and swirl the pan to spread out the batter. Cook until mostly dry on the surface, 1 to 2 minutes, flip and cook 1 minute more.