Preheat the oven to 180°C and preheat the grill to high.
Whisk eggs into flour, then add salt, half the milk, butter, and remaining milk.
Chill the batter in the fridge for 30 minutes.
Melt butter in a 20cm frying pan and cook thin pancakes until golden on both sides.
Repeat the process to make eight thin pancakes.
Whisk egg yolks with water over low heat until thick and smooth.
Slowly whisk in melted butter, then season with salt, pepper, and lemon juice.
Boil asparagus in salted water until tender, refresh in ice water, and dry.
Place ham and three asparagus spears on each pancake, roll up, and place in a dish.
Bake for 20 minutes until the edges are beginning to crisp.
Coat with hollandaise sauce and flash under the grill until gilded.