Place the diced potatoes, ham, rinsed split peas, onion, and garlic in the slow cooker.
Pour in the chicken broth and stir in the thyme, salt, and pepper.
Cover and cook on low for 7 hours, until the split peas are soft and the potatoes are tender.
Stir in the heavy cream and cook for 15 more minutes on low to heat through and thicken slightly.
Taste and adjust salt or pepper if needed before serving.