In a large bowl, sift together the flour and salt.
Use a wooden spoon to vigorously mix in the eggs and water/milk to create a thick batter.
As you are mixing, the dough should become elastic with air bubbles forming as it pulls from the edges.
Cover the bowl with a towel and allow to rest at room temperature for 10-20 minutes.
Bring a large pot of salted water to a boil, then reduce to a simmer.
Place a spaetzle press or large-holed colander over the pot and fill with batter. Slide the press back and forth or use a wooden spoon to press the batter through the holes of the colander to create the dumplings. Cook until the dumplings float to the top. Remove with a strainer, rinse with cold water, and drain.
In an 8 inch (20 centimeter) cast iron skillet, melt the butter over medium heat.
Add the diced onion and cook, stirring occasionally, until lightly golden and translucent. Season with salt, pepper, and nutmeg.
Add the cooked dumplings and toss with the butter and onions.
Fold in the shredded cheese and continue folding until melted and evenly coated. Leave the pan undisturbed for a couple of minutes to create a golden brown crust along the bottom and sides of the dumplings.
Remove from heat and serve immediately with chives and fried onions.