Bring a large pot of lightly salted water to a boil.
Add pasta, cook for 8-10 minutes or until al dente.
Drain and put into a serving dish.
In a medium saucepan heat olive oil over a medium heat.
Cook onion and garlic until transparent.
Stir in mushrooms, cook until tender.
Prepare KNORR Three Cheese Pasta Sauce following packet instructions.
Add to the saucepan followed by the cream and sage.
Toss sauce with cooked fettuccine.
Season with salt and pepper before serving.