In a bowl, combine the eggs, sugar and 1/2 teaspoon salt with 3/4 cup of the milk. Add the flour and stir until fully absorbed. Add the remaining 1 1/4 cups milk, 1/4 cup at a time, mixing by hand until the batter is smooth. Add the melted butter. Allow the batter to rest for 30 minutes, then cook the crepes.
Blanch the asparagus in lightly salted water. Cool in ice water and set aside.
Boil 1 quart of water along with the vinegar. Reduce the heat to a low simmer and poach the eggs.
One at a time, lay each crepe dark-side down in a pan over low heat. Sprinkle 2 tablespoons of the Parmesan over half of the crepe. Lay approximately 6 stalks of asparagus on top of the cheese. Zest 1/4 of a lemon directly over the asparagus. Fold the crepe over the asparagus.
Lay a slice of prosciutto over the crepe and top with the poached egg. Allow the crepe to sit on the heat for about 45 seconds to warm the cheese and asparagus. Sprinkle the poached egg with salt and pepper and fold the filled crepe into thirds. Serve warm.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.