1. Add the flour and salt to a large bowl and mix. Add the eggs, then gradually the mineral water and mix until you get a thick and gooey dough. Let it rest for about 10 minutes.

2. While the dough is resting, preheat the oven to 100°C (210°F) and place a casserole dish (heatproof) inside the oven. Place a large pot with water on the stove and bring the water to a boil. Place a Spätzle grater* on the pot and add some of the dough on top and spread it over the grater and press it through the small holes in the grater. The dough will drip into the hot water and sink to the bottom. As soon as the noodles come back up to the surface remove them with a slotted spoon from the pot, let them drain a bit and place them inside the prepared casserole dish. As soon as the bottom of the casserole is covered with one layer of spätzle season with some salt and pepper and sprinkle with some of the cheese. Repeat the process with the remaining dough and create several layers of noodles in the casserole – finish with a cheese layer.

3. Peel the onions, cut into rings and fry in a coated pan with the butter until golden brown. Add the fried onion rings on top of the cheesy spätzle and serve immediately. The dish is pretty heavy, so serve it with some light salad.