Using a mixer or mixing bowl, whisk together vigorously your chosen flour, eggs, milk (or water), and 2 tsp of salt until the batter is well combined and develops bubbles. Once the batter has been mixed, let it rest for a minimum of 30 minutes. It should feel thick and sticky when ready to cook.
While waiting for the dough to set, turn to making the gravy. Slice the mushrooms and chop the onion and garlic. In a large skillet over medium-high heat, place the butter and let it melt. Add the mushrooms, onion, and garlic and let them cook until tender, 5-10 minutes.
Reduce your heat slightly to medium and sprinkle the flour over the mushrooms evenly, then stir it in until it vanishes. Next, combine the tomato paste with the mushrooms, mixing well.
Fill a separate large pot with water and begin to bring it to a boil, adding the 1 tbsp of salt to the water. This is for cooking the dough in a few moments. Once boiling, turn the water down to a simmer.
Turn back to your gravy. Pour in the white wine or 1 cup of broth, stirring and scraping the browned base of the skillet to collect all the flavorful bits. Add the remaining broth, mixing well, and bring the whole pan to a boil.
Reduce the heat and allow the mushroom gravy to simmer for 10-15 minutes, until the gravy thickens. Add the heavy cream, if using, and salt and pepper to taste. Set aside and turn back to the spaetzle.
By now, the spaetzle dough should be ready to cook. Set yourself up for success beginning by placing a colander over a bowl to drain the spaetzle once cooked.
Press a small batch of batter through a spaetzle maker or colander into the simmering water. Work in batches to allow the noodles to cook through thoroughly and prevent them from sticking to each other.
Let each batch of dough cook for 2-3 minutes, until they float to the top. Stir occasionally, and when done use a slotted spoon to transfer the spetzle to the waiting colander to let excess water drip off.
Once all batches are done, top with your mushroom gravy and serve, garnish with parsley if desired.
