For the dough put flour and salt in a bowl. Crumble yeast over it. Heat milk and fat and add to the flour. Work into a smooth dough with the dough hooks of the hand mixer.
Cover and leave to rise in a warm place for about 40 minutes. For the filling, peel, wash and slice the kohlrabi and carrots. Clean and wash the mangetouts. Clean and wash spring onions and cut them into 4 cm long pieces.
Blanch kohlrabi and carrots in boiling salted water for 3 minutes and drain. Whisk eggs and milk and season with salt, pepper and nutmeg. Wash parsley, dab dry, chop and mix into the egg milk.
Knead the yeast dough vigorously on a lightly floured work surface. Roll out to a circle of about 30 cm Ø. Place in a greased casserole dish (26 cm Ø). Press the dough up at the edge of the baking dish, cover and leave to rise for a further 10 minutes.
Layer the vegetables on the dough. Pour egg milk over the vegetables and sprinkle pine nuts over them. Bake the vegetable cake in the preheated oven (electric cooker: 175 °C/ gas: level 2) for about 45 minutes. Take them out and let them cool down a little.
If desired, serve garnished with fresh chervil.