Topping: 1/2 cup fresh whole-wheat bread crumbs (1-1/2 slices) 1-1/2 tablespoons freshly grated Parmesan cheese 1 tablespoon butter or margarine, melted Clean leeks: Remove yellow or limp leaves. Cut off stringy roots and coarser green leaves at top, leaving leek about 7 inches long. Slit lengthwise to within 1 inch of root end. Soak in water; wash well under running water, spreading out leaves to remove all grit. Preheat oven to moderate (350°). Bring chicken broth to boiling in large skillet or Dutch oven over high heat. Add leeks; return to boiling. Lower heat to medium; cover and cook 10 to 15 minutes or until tender. Drain and reserve cooking broth. Saute garlic and thyme in butter in medium-size saucepan over medium-low heat for 1 minute or until garlic is tender, but not brown. Stir in flour and pepper; cook, stirring, about 2 minutes. Add enough additional chicken broth to reserved cooking broth to make 1 cup. Gradually add to flour mixture along with half-and-half; cook, stirring constantly, 3 to 5 minutes until smooth and thickened. Remove from heat; stir in Swiss and Parmesan cheeses. Spoon half of sauce over bottom of lightly greased 2-quart shallow baking dish. Arrange leeks over top of sauce; spoon remaining sauce on top. Prepare Topping: Combine bread crumbs, Parmesan and melted butter in bowl; toss together. Sprinkle over leeks. Bake in preheated moderate oven (350°) for 30 minutes until bubbly. To make ahead: Assemble dish the day before and refrigerate. Set dish in oven to bake about 45 minutes before serving. Nutrient Value Per Serving: 205 calories, 6 g protein, 10 g fat, 24 g carbohydrate, 405 mg sodium, 27 mg cholesterol. veg 9