Melt butter in a heavy, ovenproof skillet over medium-high heat. Add leeks and saute until softened, about 3 minutes. Add sherry, salt and white pepper and continue to cook until leeks are tender, about 5 minutes. Stir in cream and cook a couple of minutes longer to reduce the liquid slightly; remove from heat. Sprinkle on the Monterey jack cheese and then the Parmesan. Place the pan under the broiler and broil just until cheese melts and begins to turn golden around the edges. Serve immediately. Yields: 4 to 6 servings.

Note: This simple side dish is a good accompaniment to steak or roast chicken.