1. In large saucepan of boiling salted water, cook the fettuccine until al dente.
2. Drain and set aside.
3. In same saucepan, add the creamed spinach and cook over medium heat until heated through.
4. Stir in the sour cream and sauteed mushrooms, season to taste with salt.
5. Add the reserved pasta and toss to coat.
6. Transfer the mixture to a small baking dish.
7. Preheat a toaster oven to 375 degrees.
8. In a small bowl, combine the bread crumbs and cheese.
9. Sprinkle the bread crumb mixture on the pasta and bake until golden, about 10 minutes.