Before You Begin:
Prepare your slow cooker and ingredients as needed. Cooking times may vary depending on your slow cooker and ingredient thickness.
Prepare Potatoes
Slice potatoes evenly to about ⅛–¼ inch thick for even cooking. Pat slices dry with paper towels.
Prepare Cooker
Grease the inside of the slow cooker thoroughly with butter to prevent sticking.
Make Sauce
In a bowl, mix cream, cheddar, Parmesan, garlic, salt, and pepper until evenly combined.
Layer
Spread a thin layer of sauce on the bottom. Add a layer of potatoes, then sauce. Repeat layers, finishing with sauce on top.
Cook
Cover and cook on LOW for 4–5 hours, or until potatoes are tender when pierced with a fork in the center.
Optional Finish
For extra cheese topping, sprinkle additional cheddar during the last 30 minutes of cooking.
Serve
Serve warm directly from the slow cooker.