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Slow Cooker Caramelized Onions

These slow cooker caramelized onions turn buttery, golden, and jammy with almost no effort! No endless stirring for this rich, deeply flavored kitchen staple.

Prep Time
15 mins
Cook Time
10 hrs
Total Time
10 hrs 15 mins
Servings: 6 servings
Course: Side Dish
Cuisine: American

Ingredients

  • 4 large yellow onions thinly sliced
  • 2 tablespoon butter or olive oil for a vegan option
  • 1 tablespoon sugar
  • 1 tablespoon balsamic vinegar optional

Instructions

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  1. Set your slow cooker to high. Add melted butter (or olive oil), sliced onions, and sugar (if using). Stir to coat the onions evenly.
  2. Prop the lid open slightly to allow steam to escape and cook for 6-8 hours on low, stirring occasionally, until onions are golden brown and soft.
  3. Add balsamic vinegar and sherry to deglaze the slow cooker. Stir well to pick up any browned bits.

Notes

  • Keeping the lid slightly open helps excess moisture escape, allowing the onions to caramelize rather than steam. If your slow cooker doesn’t allow this, you can prop it open with a wooden spoon.
  • Stirring every few hours ensures even cooking and prevents burning at the edges.
  • The sugar helps accelerate caramelization, but you can omit it if you prefer a more natural sweetness.
  • Butter adds a rich depth of flavor, but olive oil is a great vegan alternative.
  • Store caramelized onions in an airtight container in the fridge for up to one week, or freeze them in portions for up to three months for easy use in recipes.
  • Keeping the lid slightly open helps excess moisture escape, allowing the onions to caramelize rather than steam. If your slow cooker doesn’t allow this, you can prop it open with a wooden spoon.
  • Stirring every few hours ensures even cooking and prevents burning at the edges.
  • The sugar helps accelerate caramelization, but you can omit it if you prefer a more natural sweetness.
  • Butter adds a rich depth of flavor, but olive oil is a great vegan alternative.
  • Store caramelized onions in an airtight container in the fridge for up to one week, or freeze them in portions for up to three months for easy use in recipes.