Ask your butcher to split the ham hock in half. Slideshow: More Crock Pot and Slow Cooker Recipes
Heat a slow cooker on high until hot. Stir in the butter until melted, then add the ham hock and brown, turning once, until golden, about 5 minutes. Stir in the onions, garlic, 1/2 teaspoon salt and 1/4 teaspoon pepper and cook, stirring occasionally, until golden, about 6 minutes. Peel the potatoes and cut into bite-sized cubes. Reduce the heat to low and stir in the potatoes and stock. Cook the soup until the potatoes are starting to fall apart, about 6 hours. Remove the ham hock and let cool to warm. Remove the meat, discarding the bones and return the meat to the slow cooker. Season the soup with salt and pepper to taste then serve.