In a bowl whisk together flour, eggs, melted (but cold) butter, milk, water and a pinch of freshly grated nutmeg. Stir to get a nice, smooth mixture.
Bring a large pot of salted water to a boil. Working in batches (3x), use a spaetzle maker or a grater with large holes to press the batter through. Cook for about 2 - 3 minutes in a boiling water. Transfer to a bowl filled with cold water to stop the cooking (or use immediately.) Drain the spaetzle, heat a bit of butter in a large pan and cook them for about a minute, just so that they get a nice, golden color.
Serve your spaetzle with different sauces, with mushrooms or steak/other meat. Store in an airtight container in a fridge for up to 5 days or freeze for up to a month.