Slow Cooker Caramelized Onions

These slow cooker caramelized onions are unbelievably easy to make, and only require 2 main ingredients!

Prep Time: 10 mins

Cook Time: 12 hours


3-4 pounds white, yellow or red onions, peeled and thinly sliced

3 tablespoons butter (or olive oil), melted

salt and pepper

optional: 1 tablespoon of brown sugar and 2 teaspoons of balsamic vinegar


  1. Add onions to the bowl of your slow cooker.  Drizzle the melted butter evenly over the top of them, then toss with a spoon (or with your hands) until the onions are evenly coated in the butter.
  2. Cook on low for 8-10 hours, stirring once or twice if desired, until the onions are a rich golden brown and caramelized.  Season with salt and pepper (and brown sugar and/or balsamic, if desired), and stir to combine.
  3. If your onions are really juicy at this point, set the lid an inch or so ajar.  If they are not, leave the lid on regularly to seal in the moisture.  Then continue cooking the onions for an additional 3-4 hours until most of the extra liquid has evaporated and the onions are a deep golden brown, and thick and “jammy”.
  4. Serve the onions immediately, or cover and refrigerate for up to 3 days.  Or freeze for up to 3 months.