In a large cast-iron skillet, heat 3 tablespoons olive oil over medium-high heat. Add the mushrooms, season with salt and pepper, and cook for 8-10 minutes, stirring. Add the rosemary, sage, thyme, and garlic and cook for 2 minutes longer, stirring.
Bring a large pot of salted water to a boil over high heat. Add the fettuccine and cook until it is al dente. Drain the pasta, reserving 1 tablespoon of the water.
Add the pasta, the additional 1 tablespoon olive oil, and reserved water, to the skillet. Cook for 2 minutes, gently mixing until combined.
Transfer the pasta to a serving platter or individual plates. Sprinkle black pepper over the top, if desired. Serve immediately.