From Simple Vegetarian Pleasures: This sauce is very simple and elegant. You don't need much cheese or any other additions because the wonderful flavor of leeks carries the dish. ::I really like it because it's very easy to make and not too rich:: Serves 3-4
2 large leeks
1 TB unsalted butter
1/2 C. heavy cream
1/4 tsp. salt
freshly ground black pepper to taste
1 lb. frozen cheese tortellini
1 TB grated Paremesan cheese
1. Bring a large stockpot of water to a boil.
2. Meanwhile slice the roots off the leeks, plus all but 2 in. of green tops. Slice the leeks in half lengthwise. Under cold running water rinse the leeks, thumbing through all the leaves to dislodge any hidden dirt. Do this thoroughly to rid them of all their dirt. Thinly slice the leeks. You can use the light green tops, but discard any dark green tops. You should get about 2 1/2 C. sliced leeks.
3. Melt the butter over med. heat in a large skillet. Add the leeks and saute until tender, about 10 min. Stir frequently, and keep an eye on the leeks so they don't get at all brown.
4. Pour in the cream, salt and pepper. Heat just until it boils, then turn the heat very low to keep the sauce warm.
5. Drop the tortellini in the boiling water and cook until al dente, about 5 min. Drain in a colander, then mix into the sauce along with the Parmesan cheese. Toss and serve.