1 tablespoon unsalted butter, melted and cooled, plus more for the skillet
Superfine sugar, as needed
Lemon wedges, as needed
To prepare the batter, combine the eggs, egg yolks, milk, and cream in a large liquid measuring cup, and whisk until smooth. In a large bowl, whisk together the flour, sugar, and salt. Make a large well in the center of the flour mixture and pour in the milk mixture. Gently whisk the center of the milk mixture, very gradually grabbing the flour around the edges, little by little, until it is all combined. Go slowly to avoid lumps. Alternatively, blend all of the crêpe batter ingredients in a blender until smooth. Strain the mixture through a fine-mesh sieve into a bowl, then whisk in the butter, vanilla bean, and vanilla seeds. Cover and refrigerate for at least 4 hours or up to overnight.
Whisk the crêpe batter well until smooth and discard the vanilla bean. Melt a little bit of butter in a 10-inch nonstick skillet over medium heat and let the pan get hot. Add a scant 1/4 cup (about 3 tablespoons) of the crêpe batter to one side of the pan and quickly tilt and swirl the pan to evenly coat the bottom with the batter. Cook until very lightly golden and set, about 30 seconds. Slide a small offset spatula under the edge of the crêpe to loosen it, and use a rubber spatula or grab onto it with your fingers, and quickly flip it over. They will be hot, so work quickly. Cook until light golden brown, 30 seconds to 1 minute. Sprinkle with the superfine sugar and fresh lemon juice to taste. Fold the crêpe in quarters and slide onto a plate. Repeat with the remaining batter.