8 oz. pkg. med. fettuccine noodles
2/3 c. grated Parmesan cheese
1/4 c. butter
1 c. sour cream
1 egg yolk

While noodles are cooking, beat egg yolk lightly with fork and add to sour cream; melt butter. Place drained, hot noodles in warm serving bowl. Pour egg mixture, melted butter and about half of grated Parmesan cheese over noodles. Toss noodles with fork and spoon until well blended, adding balance of cheese a little at a time while tossing. Top with additional grated cheese, if desired and serve immediately.

Pasta Primavera: Same as above except add steamed broccoli, cauliflower and carrots.