PREPARATION:
- To prepare leeks, remove any withered outer leaves. Cut off 1 inch of leaf tops; discard. Cut off roots, then cut leeks in half crosswise. Make slit down length of each leek half, being careful not to cut through leek completely. Rinse thoroughly. Tie 2 leek halves together with kitchen string; repeat with remaining leeks. Place leeks in Dutch oven; pour in enough lightly salted water to cover. Bring to a boil over high heat. Reduce heat to low; simmer 6 to 8 minutes or until leeks are tender. Drain and pat dry. Remove strings.
- Preheat oven to 350°F. Place tomatoes in bottom of 13X9-inch baking dish.
- Melt butter in medium saucepan over medium heat. Add celery; cook 3 minutes or until celery is crisp-tender. Remove celery with slotted spoon; arrange evenly over tomatoes. Reserve butter in saucepan.
- Wrap 1 ham slice around each leek half. Arrange, seam side down, in single layer in baking dish.
- Add garlic to reserved butter in saucepan. Cook and stir over low heat 30 seconds. Stir in flour, salt, pepper and nutmeg. Cook 2 minutes, stirring constantly. Gradually whisk in milk and half-and-half until smooth. Cook until mixture boils and thickens, whisking constantly. Remove from heat. Stir in 3/4 cup cheese; continue to stir until cheese melts.
- Pour cheese sauce evenly over leeks. Sprinkle with remaining 1/4 cup cheese and bread crumbs. Bake 30 minutes or until lightly browned and bubbly.
