Sauté onion and garlic in hot oil in a large Dutch oven over medium-high heat 5 minutes or until onion is tender. Stir in chicken, next 3 ingredients, and 2 cans navy beans. Coarsely mash remaining can navy beans, and stir into chicken mixture. Bring to a boil, stirring often; cover, reduce heat to medium-low, and simmer, stirring occasionally, 10 minutes. Serve with desired toppings.