Grate the gouda finely. Put 350 g flour, butter in pieces, lemon juice, crème fraîche, 1 teaspoon salt and cheese into a mixing bowl and knead with the dough hooks of a hand mixer. Then knead on a floured work surface with your hands to a smooth dough.
Wrap in cling film, chill for about 1 hour.
Meanwhile peel the carrots, possibly wash and dice them. Clean, wash and chop the zucchini. Peel, wash and chop the potatoes. Peel and chop the onions. Heat the oil in a large pan.
Fry the potatoes for about 10 minutes while turning them.
Add the carrots, onions and courgettes and fry for another 5-8 minutes while turning. Season with salt and pepper, remove from the pan and drain on kitchen paper.
For the sauce, grate the Gruyère and Emmental finely. Mix 50 g flour and milk well in a saucepan. Bring to the boil while stirring and simmer at low heat for 4-5 minutes. Stir in grated cheese, remove pot from heat.
Mix eggs and sour cream. Pour into the pot and stir until smooth. Season vigorously with salt, pepper and nutmeg. Roll out the dough on a floured work surface to a circle (approx. 40 cm Ø).
Place in a greased sewing form (30 cm Ø, edge height 5 cm) and press down. Prick the bottom several times with a fork and sprinkle with breadcrumbs.
Spread the potato and vegetable mixture evenly on top and pour the cheese sauce over it. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) on the lower shelf for 40-45 minutes.
After about half the baking time, cover carefully with aluminium foil.
Wash parsley, shake dry and chop finely. Remove from the oven, place on a cake rack and leave to rest for 10-15 minutes. Remove from the pan, arrange and sprinkle with parsley. Serve with crème fraîche sprinkled with cheese.