Put 3 eggs and 1/2 teaspoon salt in a bowl and mix. Gradually stir in milk and flour. Finally add oil and mineral water and stir in. Cover the pancake batter and set aside (approx. 20 minutes).
Wash and peel the asparagus and cut off the woody ends. In a large saucepan, bring salted water with sugar and 10 g butter to the boil, add the asparagus and cook covered for about 15 minutes. Lift the asparagus out of the stock, drain and let it cool down.
Add the asparagus skins and segments to the asparagus stock, bring to the boil, cover and simmer at low heat for about 10 minutes. Pour the stock through a sieve and use for an asparagus soup. For the pancakes, put some butter in a pan (approx. 18 cm Ø) and heat it up.
Put 1/8 of the dough into the pan and bake a golden brown pancake while turning. Bake 7 more pancakes in a row and let them cool down. Put a slice of ham on each pancake.
Place 3-5 asparagus spears on top and roll them up in the pancake. Fill all pancakes one after the other and place them rolled up in a greased casserole dish. Whisk 4 eggs and cream and season with salt, pepper and nutmeg.
Sprinkle the pancakes with grated cheese and pour the egg cream over them. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 30-40 minutes. Garnish with chervil.