In a slow cooker, combine potatoes, garlic, and bay leaf. Pour broth over potatoes.
Cover and cook on low for 6 to 8 hours or on high for 3 to 4 hours.
Drain potatoes in a colander over a bowl to catch the cooking liquid. Discard bay leaf. Return potatoes to slow cooker and mash lightly with a potato masher.
In a small saucepan, heat cream and butter until steaming and butter almost melts. Add cream mixture, salt, and enough of the reserved cooking liquid to mashed potatoes to reach desired consistency.
Use potato masher or hand mixer if you prefer a smoother mashed potato.
To serve, transfer potatoes to a serving bowl. Sprinkle with freshly ground black pepper and desired toppings.