Knead flour, salt, butter and 1 egg to a smooth dough. Wrap in foil and chill for about 30 minutes. Wash, clean and drain the mangetouts. Clean, peel and wash the carrots.
Steam the carrots in a pot covered with a little water for 6-7 minutes, remove and rinse in cold water. Halve the sugar snap peas. Stir sour cream, milk and 3 eggs until smooth. Sift the starch on top and fold in.
Season to taste with salt, pepper and nutmeg. Wash the chervil, dab dry, remove coarse stalks. Finely chop the rest of the chervil. Stir the chervil into the egg cream. Roll out the dough on a floured work surface and line a greased, floured tart with a lift-off base (26 cm Ø).
Finely crumble the rolls into breadcrumbs. Sprinkle the base with 1 tbsp. breadcrumbs. Spread half the sugar snap peas on top. Spread the carrots like spokes on top, possibly cutting them smaller. Spread the remaining sugar snap peas in the gaps.
Pour over egg cream and bake in a preheated oven (electric range: 175 °C/ convection oven: 150 °C/ gas mark 2) for 35-45 minutes until golden brown.