This Slow Cooker Potato and Onion Bake is the ultimate comfort food—simple, hearty, and full of rich, savory flavor. Tender sliced potatoes cook slowly with sweet, caramelized onions, soaking up buttery seasoning until perfectly soft and golden. It’s an easy, budget-friendly side dish that pairs beautifully with almost any meal.
Prep Slow Cooker: Lightly grease the inside of a 4- to 6-quart slow cooker with a bit of butter.
Prep Veggies: Slice the potatoes and onions into thin, even rounds (about 1/8-inch thick).
Butter Bottom: Drizzle 1 to 2 teaspoons of melted butter into the bottom of the slow cooker.
First Layer: Add a single, slightly overlapping layer of potato slices to the bottom. Sprinkle a loose handful of sliced onions over the potatoes.
Butter & Season: Drizzle a teaspoon of melted butter over this layer. (Add a tiny pinch of salt and pepper here if desired, though the salted butter is usually enough).
Repeat Layers: Repeat the layers of potatoes, onions, and melted butter until all ingredients are used. Finish with a final drizzle of butter on top.
Cook: Cover and cook on LOW for 6 to 7 hours, or on HIGH for 3 to 4 hours, until potatoes are tender.
Rest & Serve: Let rest with the lid off for 10 minutes to allow the juices to thicken. Scoop deep to get every layer, spooning the bottom juices over the top before serving. Enjoy!