Peel potatoes and dice into 1/2-inch cubes. In a 4-quart saucepan fry bacon in butter until golden crisp; add garlic and cook over medium-low heat. Add potato and leeks and cook, stirring occasionally, 2 minutes. Stir in broth and simmer, uncovered, 15 minutes, or until potato is very tender. Stir in milk, parsley, and season with salt and pepper to taste and heat over medium heat, stirring occasionally, until hot.