Peel the potatoes and cut into half-inch cubes. Chop the onion into a medium dice. (Note: sizes of onions vary greatly so adjust the recipe accordingly to your preferences). Crush or press the garlic. Add the potatoes, onion, broth, garlic, butter, salt and pepper to the crock pot. Stir gently. Cover, cook on low for 4 hours or until potatoes are tender. When potatoes are tender, mash the mixture with a potato masher or a large wooden spoon until chunky but not completely mashed. Stir in the cream, Cheddar cheese, and chopped chives, and turn the heat to high. Cook for 15 minutes longer or until heated through. To serve, ladle soup into individual bowls and top with a dollop of sour cream, crumbled bacon, and additional shredded cheese, if desired.