Slow Cooker Caramelized Onions

😊 Slow cooker caramelized onions are one of those set-it-and-forget-it recipes that turn out incredibly sweet and jammy.

Slow Cooker Caramelized Onions

Ingredients

3–4 lbs onions (yellow or sweet work best), thinly sliced

3 tablespoons butter (or olive oil)

½ teaspoon salt

Optional:

1 teaspoon sugar (helps speed caramelization)

1 tablespoon balsamic vinegar (for depth at the end)

Fresh thyme or bay leaf

Instructions

Prep the Onions

Peel and thinly slice the onions.

Add them to the slow cooker.

Season

Add butter, salt, and sugar (if using).

Toss gently to coat.

Cook

Cover and cook on:

HIGH for 4–5 hours, or

LOW for 8–10 hours

Stir every 1–2 hours if possible (not mandatory, but helps even color).

Finish

When onions are deep golden-brown and jammy, stir in balsamic vinegar (if using).

Taste and adjust salt.

Tips for Best Results

Leave the lid slightly ajar for the last 1–2 hours to let moisture escape.

If onions are soft but pale, uncover and switch to HIGH.

Don’t rush—true caramelization takes time.

Storage & Uses

Refrigerate: Up to 5 days

Freeze: Up to 3 months (ice cube trays work great!)

Perfect for:

Burgers & hot dogs

Grilled cheese

Pizza & flatbread

Mashed potatoes

Steak or pork chops