In a large skillet, heat the olive oil over medium heat. Add the chopped onion, carrots, and celery. Sauté for about 5 minutes until the vegetables are softened. Add the minced garlic and cook for an additional minute until fragrant.
In the crockpot, combine the rinsed navy beans, sautéed vegetables, diced ham, chicken broth, thyme, rosemary, bay leaf, salt, and pepper. Stir to combine.
Cover and cook on low for 8 hours or on high for 4 hours, until the beans are tender.
Before serving, remove the bay leaf and adjust seasoning with additional salt and pepper if needed.
Serve hot, garnished with fresh parsley if desired.