Put flour, 1/4 teaspoon of salt, butter in pieces and 1 egg in a bowl. Knead quickly to a smooth dough and cover and chill for about 30 minutes. Wash the green asparagus and cut off the woody ends.
Steam in a pot with little salted water for about 8 minutes until firm to the bite. Wash and peel white asparagus and cut off woody ends. Remove green asparagus with a skimmer and rinse in cold water.
Boil 1.5 litres of water together with 20 g salt and 30 g sugar in a larger pot. Add the asparagus and cook at low heat for about 6 minutes until al dente. Also take them out and quench.
Whisk 4 eggs and cream thoroughly, season to taste with salt, pepper and nutmeg. Roll out the dough into a circle (approx. 30 cm Ø) on a floured work surface. Put it into a greased tart tin (26 cm Ø) sprinkled with flour, press the rim slightly.
Cut off any excess dough. Halve the asparagus diagonally and distribute in the form. Wash the chervil, dab dry, chop up to about 2 stems, chop coarsely and add to the egg cream. Pour the egg-cream into the tin and bake in a preheated oven (electric range: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 35 minutes until golden brown.
Remove the quiche, allow to cool briefly and garnish with the chervil.