Soak porcini — Place dried porcini in 1/2 cup warm water for 20 minutes. Strain and reserve the soaking liquid; set mushrooms aside. (Prep step while heating pasta water.)
Cook pasta — Bring a large pot of salted water to a boil. Cook pasta until just shy of al dente (about 1–2 minutes less than package directions). Reserve 1/2 cup pasta water, then drain and set aside.
Sauté aromatics — In a large skillet over medium heat, warm olive oil and butter. Add shallots and cook until softened, ~3–4 minutes. Add garlic and cook 30 seconds until fragrant.
Brown mushrooms — Increase heat to medium-high. Add fresh mushrooms and a pinch of salt; sauté until deeply browned and their moisture has mostly evaporated, about 6–8 minutes. Add rehydrated porcini (and a splash of their soaking liquid if desired) and cook 1–2 more minutes.
Deglaze — Pour in white wine (if using) and reduce by half. Add reserved porcini liquid or stock and simmer briefly to concentrate flavors.
Create the cheese emulsion — Reduce heat to low. Add small handfuls of grated nettle cheese, stirring constantly to melt. Add reserved pasta water a little at a time to form a silky sauce. Do not boil once cheese is added. If sauce looks grainy, remove pan from heat and whisk in a splash of cold pasta water or a tablespoon of cream.
Combine pasta and sauce — Add drained pasta to the skillet and toss gently to coat. Adjust consistency with more pasta water if necessary. Season with salt and cracked black pepper.
Finish & serve — Remove from heat and fold in lemon zest and chopped parsley. Plate, top with extra grated nettle cheese and toasted nuts if using. Serve immediately with crusty bread and a green salad.
