Step 1 of 5
Boil the pasta. Cook fettuccine in well-salted boiling water until al dente. Reserve 1/2 cup pasta water, then drain.
Step 2 of 5
Sauté the mushrooms. In a large skillet over medium heat, melt the butter with the olive oil. Add the mushrooms and cook until golden and the released liquid has evaporated.
Step 3 of 5
Add aromatics. Stir in the garlic and torn prosciutto; cook until fragrant.
Step 4 of 5
Build the sauce. Add the peas and heavy cream; simmer to thicken slightly. Stir in the Parmesan and season with salt and pepper.
Step 5 of 5
Toss and serve. Add the drained fettuccine to the skillet, tossing to coat and loosening with reserved pasta water as needed. Serve immediately with extra Parmesan.