Place the rinsed split peas in the slow cooker. Add the diced ham, onion, carrots, celery, and garlic.
Pour in the chicken broth and add the bay leaf and thyme. Season with salt and black pepper.
Stir everything together so the ingredients are evenly distributed.
Cover and cook on low for 8 hours or on high for 4 hours until the peas are soft and the soup has thickened.
Remove the bay leaf. Taste and adjust salt and pepper if needed.
Ladle the soup into bowls and serve with the slices of crusty bread on the side.