Caramelized Onions in a Slow Cooker

Caramelized onions are a versatile ingredient that can elevate the flavor of many dishes, from soups and stews to burgers and pizzas. Making caramelized onions in a slow cooker is a simple and hands-off method that yields perfectly sweet and golden onions with minimal effort. Follow this easy recipe to make a batch of delicious caramelized onions that you can use throughout the week.


  • 3 pounds onions (yellow, white, or a mix), thinly sliced
  • 3 tablespoons butter, melted (or olive oil for a vegan option)
  • 1 teaspoon salt
  • 1 teaspoon sugar (optional, for added sweetness)
  • 1/2 teaspoon black pepper (optional)
  • 1 tablespoon balsamic vinegar (optional, for added depth of flavor)


1. Prepare the Onions:

  • Peel the onions and slice them thinly. You can use a sharp knife, a mandoline slicer, or a food processor with a slicing attachment to make the process quicker and more uniform.

2. Combine Ingredients in the Slow Cooker:

  • Place the sliced onions in the slow cooker.
  • Drizzle the melted butter or olive oil over the onions and toss to coat them evenly.
  • Sprinkle the salt and sugar (if using) over the onions and mix well.

3. Cook the Onions:

  • Cover the slow cooker with the lid and set it to cook on low heat.
  • Cook the onions for 10-12 hours, stirring occasionally. The long cooking time allows the onions to slowly caramelize and develop a deep, rich flavor.

4. Optional Enhancements:

  • If desired, add black pepper and balsamic vinegar to the onions during the last hour of cooking. Stir to combine and continue cooking until the onions reach the desired level of caramelization.

5. Store and Use:

  • Once the onions are caramelized to your liking, transfer them to an airtight container.
  • Store the caramelized onions in the refrigerator for up to one week or freeze them in portions for longer storage.

Tips for Success:

  • Choosing Onions: Yellow onions are the most commonly used for caramelization due to their balance of sweetness and pungency. However, white onions and even red onions can also be used for a different flavor profile.
  • Stir Occasionally: While the slow cooker does most of the work, stirring the onions every few hours ensures even caramelization and prevents any onions from sticking to the sides.
  • Adjusting Sweetness: If you prefer a less sweet flavor, you can omit the sugar or reduce the amount. The natural sugars in the onions will still caramelize beautifully over time.
  • Batch Cooking: This recipe is great for batch cooking. Make a large batch and store the onions in small portions to use in various recipes throughout the week.

Caramelized onions made in a slow cooker are a convenient and foolproof way to add a depth of flavor to your dishes without the need for constant monitoring. This method allows you to achieve perfectly caramelized onions with minimal effort, freeing up your time for other kitchen tasks. Whether you use them to top a juicy burger, stir them into a comforting soup, or add them to a gourmet pizza, these slow-cooked caramelized onions will enhance any dish they touch. Enjoy the rich, sweet, and savory flavors of homemade caramelized onions with this easy recipe!

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