Slow Cooker Potato Onion Bake

A hearty, comforting side dish that practically cooks itself — tender layers of potatoes and sweet onions slow-cooked in a creamy, cheesy sauce until golden and irresistible.

Prep Time: 15 minutes
Cook Time: 4–5 hours on LOW (or 2–3 hours on HIGH)
Total Time: 4 hours 15 minutes
Servings: 6–8

Ingredients

• 6 medium potatoes (about 2 lbs), peeled and thinly sliced

• 2 large onions, thinly sliced

• 3 tablespoons unsalted butter

• 1 can (10.5 oz) condensed cream of mushroom soup (or cream of celery), do not dilute

• 1 cup milk

• 1 cup shredded cheddar cheese

• 1/2 cup grated Parmesan cheese

• 1 teaspoon garlic powder

• 1/2 teaspoon onion powder

• 1/2 teaspoon salt

• 1/4 teaspoon black pepper

• 1/2 teaspoon dried thyme (optional)

• Fresh chopped parsley, for garnish (optional)

Instructions

1. Prepare the slow cooker. Lightly grease the inside of a 5–6 quart slow cooker with butter or non-stick spray.

2. Layer the potatoes and onions. Place half the sliced potatoes in an even layer at the bottom. Top with half the sliced onions. Repeat with the remaining potatoes and onions.

3. Make the sauce. In a medium bowl, whisk together the condensed soup, milk, garlic powder, onion powder, salt, pepper, and thyme (if using) until smooth.

4. Pour and add cheese. Pour the sauce evenly over the potatoes and onions. Sprinkle the shredded cheddar and Parmesan cheese over the top.

5. Add the butter. Cut the butter into small pieces and dot them over the top of the cheese.

6. Cook. Cover and cook on LOW for 4–5 hours, or on HIGH for 2–3 hours, until the potatoes are fork-tender and the edges are golden and bubbly.

7. Rest and serve. Turn off the slow cooker and let the bake rest for 10 minutes before serving. Garnish with fresh chopped parsley if desired.
   

   Tips

   • Slice evenly: Cut the potatoes and onions to a uniform thickness so they cook evenly.

   • Don't stir: Resist the urge to stir during cooking — layering helps everything cook evenly and prevents mushiness.

   • Add a topping: For a crispy finish, transfer the bake to a baking dish, top with extra cheese and breadcrumbs, and broil for 2–3 minutes.

   • Make it heartier: Add cooked crumbled bacon or sliced smoked sausage between the layers.

   • Cheese choice: Gruyère, mozzarella, or a cheese blend all work well in place of cheddar.