In a large bowl, combine the torn bread (or bread crumbs), milk, eggs, and Parmesan cheese.
Mix thoroughly and set aside to let the bread soften.
Place a large skillet over medium heat and add the olive oil or butter.
Once hot, add the reconstituted porcini and fresh mushrooms.
Season with salt and pepper and cook for a few minutes.
Stir in the minced garlic and rosemary.
Continue cooking, stirring occasionally, until the mushrooms are tender and have released their liquid, about 5-7 minutes.
Add the cooked mushroom mixture to the bread mixture in the bowl.
Stir everything together until well combined.
Let the mixture rest for at least 15 minutes. You can also cover and refrigerate it for up to a day.
Bring a large pot of vegetable stock or salted water to a boil, then reduce to a steady simmer.
Check the consistency of your dumpling mixture. If it's too soft to hold a shape, stir in more bread crumbs. If it's too stiff, add a splash of milk.
Form the mixture into balls about 1. 5 inches in diameter.
Gently drop the dumplings into the simmering water as you form them.
Cook until they float to the surface, which should take about 5 minutes.
Remove them with a slotted spoon and serve immediately.
Don't discard the flavorful liquid from reconstituting the porcini.
Strain it through a coffee filter and add it to your soup broth for an extra layer of umami.
