1Place potatoes in 3 1/2- to 4-quart slow cooker. Stir in garlic, butter, salt, pepper and water.
2Cover and cook on high heat setting 4 to 6 hours or until potatoes are tender.
3Do not drain potatoes. Mash potatoes slightly with potato masher. Add half-and-half and cheese; continue mashing until desired consistency and some lumps remain. Stir in basil just before serving. Potatoes will hold on low heat setting up to 2 hours.