Cook bacon in a large Dutch oven over medium heat until crisp; crumble and set aside, reserving drippings (about 2 tablespoons) in pan. Add leeks and celery to pan with drippings; cook, stirring occasionally, over medium-high heat 6 minutes or until tender. Add garlic and rosemary; cook 1 minute. Add carrot and next 5 ingredients; bring to a boil. Reduce heat, and simmer, uncovered, 25 minutes or until vegetables are tender. Discard ham bone. Ladle into individual soup bowls; sprinkle with reserved crumbled bacon and parsley. Garnish, if desired.
For added flavor, include the ham bone in the pot. Toss in any other remaining vegetables, including green beans, Brussels sprouts, sweet potatoes, or roasted potatoes.