CSA boxes are a wonderful way to support local farms and enjoy fresh, seasonal produce. But what do you do when you find yourself swimming in onions? The answer is simple: make a big batch of caramelized onions in your slow cooker. These rich, golden onions add a depth of flavor to countless dishes and can be a game-changer in your kitchen. The best part? They can be frozen, so you’ll always have this delicious ingredient on hand.
Caramelized onions are a kitchen essential, perfect for enhancing the flavors of soups, stews, sandwiches, and more. The slow cooker method is a game-changer—set it, forget it, and come back to a pot full of savory, sweet, perfectly caramelized onions. No more standing over a hot stove for hours. Just let the magic happen while you go about your day.
Creative Uses for Caramelized Onions
- Caramelized Onion Flatbread: Spread the onions over a pre-made flatbread, add some bacon and Gruyère, and bake until golden. A perfect appetizer or light dinner. Get the recipe here.
- French Onion Soup: A classic favorite. Use your caramelized onions as the base, add beef broth, and top with a toasted baguette slice and melted cheese.
- Gourmet Grilled Cheese: Layer caramelized onions with sharp cheddar or Swiss cheese for an elevated grilled cheese experience.
- Burger Upgrade: Add a spoonful of caramelized onions to your next burger for a burst of sweet, savory flavor.
- Pasta Perfection: Toss caramelized onions with cooked pasta, a splash of pasta water, and a sprinkle of Parmesan for a quick, flavorful meal.
Storing Your Caramelized Onions
In the Fridge:
- Let the onions cool completely.
- Transfer them to an airtight container.
- Store in the refrigerator for up to one week.
In the Freezer:
- Let the onions cool completely.
- Portion them into freezer-safe bags or containers.
- Label and date the containers.
- Freeze for up to three months.
To use frozen caramelized onions, simply thaw them in the refrigerator overnight or warm them up directly in your dish. Having these flavorful onions ready to go will save you time and add a delicious depth to your cooking.
Slow Cooker Caramelized Onions
- Slow cooker (at least 6-quart capacity)
- 3 lbs onions (yellow, white, or a mix)
- 3 tablespoons unsalted butter, melted
- 1 teaspoon salt
- 1 tablespoon brown sugar (optional, for added sweetness)
- Peel the onions and cut them in half. Slice each half into thin half-moons.
- Place the sliced onions into the slow cooker. Drizzle with melted butter, sprinkle with salt and brown sugar (if using). Toss everything together directly in the slow cooker until the onions are evenly coated.
- Set the slow cooker to low heat. Cover and cook for 10-12 hours, stirring every 2-3 hours to ensure they cook evenly.
- Around the 8-hour mark, check the onions. If they have too much liquid, place the lid back on the slow cooker slightly ajar. Continue cooking until the liquid is evaporated and the onions become jammy and deeply caramelized.
- Once the onions are fully caramelized, turn off the slow cooker. Let them cool slightly before transferring to an airtight container. They can be stored in the refrigerator for up to a week or frozen for up to 3 months.
- For a slightly different flavor profile, you can add a splash of balsamic vinegar or a pinch of thyme during the last hour of cooking.
- You can easily scale this recipe up or down by using 1 tbsp of melted butter for every 1lb of onions. Just be sure that you don't overload your slow cooker if scaling up (you'll need room to stir), and don't under-fill it if scaling down or else your onions may burn instead of caramelize (minimum of 1lb if you're using a 6 quart slow cooker). Smaller batches will caramelize quicker, whereas larger batches will need longer to properly caramelize.
