Crockpot scalloped potatoes are cooked tender in the crock pot in the easiest dump-and-pour milk sauce, thinly sliced onions, and cheese. Layer these ingredients into your slow cooker and it cooks into a creamy, golden, and bubbly potato casserole! This is the way to make cheesy scalloped potatoes from scratch with no soup cans or boxed stuff! It's a quick and easy side dish to bring to a potluck or Holiday, and you can prep it ahead of time and let it slowly cook later! It's my favorite Scalloped Potatoes recipe!
Grease the inside of your crock pot with oil or cooking spray. Layer with 1/3 of the onions, potatoes, and cheese. Repeat twice ending with potatoes and cheese.
In a large measuring cup mix together the milk, cornstarch, yellow mustard, salt, and pepper.
Pour the milk mixture over all the layers and cook on high for 3-4 hours until the potatoes are tender and the sauce is golden and bubbly.
Allow the potatoes to rest unplugged for 20 minutes before serving.