Slow Cooker French Onion Meatballs

Name: Slow Cooker French Onion Meatballs
Prep time: 10 min
Total time: 310 min
Ingredients: 36 ounce frozen meatballs; 2 large sweet onions (thinly sliced into half moons); 3-5 garlic cloves (minced); 2 cups low sodium beef broth; 10.5 ounces condensed French onion soup (1 can); 1 tablespoon balsamic vinegar; 1 ½ teaspoons fresh thyme (minced); ¾ teaspoon black pepper (to taste); 2 tablespoons cornstarch; 1 cup shredded Gruyere cheese; Fresh thyme or parsley (for garnish (optional))

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These Slow Cooker French Onion Meatballs simmer in a rich onion sauce with caramelized onions and gooey Gruyere melted on top. Simple to make and loaded with classic French onion soup flavor, they make the perfect easy and delicious weeknight dinner.

Meatballs in a rich brown sauce topped with melted cheese and garnished with herbs, being scooped from a pot with a wooden spoon.

French Onion Meatball Recipe

When it comes to cooking dinner, I’m all about time-saving shortcuts, and these Slow Cooker French Onion Meatballs are a favorite. They’ve got everything you love about classic French onion soup, only in juicy, cheesy meatball form. The onions cook low and slow until golden and sweet, and the Gruyere melts over the top into the perfect gooey layer.

But the real secret to making this recipe super easy is using frozen meatballs. They save so much time, and once they’ve simmered in that sauce, they’re just as tender and flavorful as homemade. Pile them over mashed potatoes, egg noodles, or serve with crusty bread for dipping and you’ve got a dinner that’ll have everyone begging for seconds.

If your family loves meatballs as much as mine, you’ll also want to try my Buffalo Chicken Meatballs for a spicy kick and my Sweet and Sour Meatballs for something tangy and fun.

A bowl of meatballs topped with melted cheese and herbs, surrounded by bread slices, parsley, a blue checkered napkin, and salt and pepper shakers.

Why We Love This Recipe

Classic flavors: It takes everything comforting about French onion soup and transforms it into juicy, cheesy meatballs.
Easy dinner recipe: The slow cooker does the heavy lifting, so you get a rich onion sauce without spending hours in the kitchen.
Versatile: They aren’t just for dinner. These meatballs make a delicious hearty appetizer for game day, parties and holiday gatherings.
Feeds a crowd: This is an easy dinner idea that makes plenty, and it reheats beautifully, great when you you’re feeding a crowd.

Ingredients

Frozen meatballs: Use beef, Italian, or turkey meatballs, whatever you prefer.
Sweet onions: Thinly sliced into half-moons so they caramelize nicely.
Garlic cloves: Freshly minced for the best savory flavor.
Beef broth: Low sodium keeps the sauce from being too salty.
French onion soup: Canned condensed soup adds rich flavor quickly.
Balsamic vinegar: Balances the sweetness of the onions with a little tang.
Fresh thyme: Earthy flavor that pairs perfectly with onions and beef.
Black pepper: Just enough to enhance the savory notes.
Cornstarch: Thickens the sauce so it clings to the meatballs.
Gruyere cheese: Melts into a gooey, cheesy topping for that French onion finish.
Parsley or thyme: Optional garnish for a fresh pop of color.

Find the full printable recipe with measurements and directions in the recipe card below.

How To Make French Onion Meatballs

Step 1. Place frozen meatballs in the crockpot.

Step 2. Top with sliced onions and minced garlic.

A black slow cooker filled with frozen meatballs, viewed from above on a light-colored surface.

A slow cooker filled with sliced onions, garlic, and frozen meatballs on a light-colored surface.

Step 3. In a large bowl or measuring cup, whisk together the beef broth, French onion soup, balsamic vinegar, thyme, pepper, and cornstarch.

Step 4. Pour the French onion sauce over the meatballs, onions, and garlic.

A glass bowl filled with a brown liquid mixture speckled with black and green herbs, placed on a light-colored surface.

Sliced onions, meatballs, and seasoning are arranged in a black slow cooker on a light countertop.

Step 5. Cover and cook on low for 3-5 hours, stirring once halfway through.

Step 6. Just before serving, sprinkle Gruyere over the top. Cover for 5-10 minutes until cheese is melted. Garnish with parsley or thyme and serve hot.

A slow cooker filled with meatballs and sauce, viewed from above on a light surface.

A black slow cooker filled with cooked meatballs topped with melted cheese and garnished with chopped herbs, viewed from above.

Storage Instructions

Store leftover meatballs in an airtight container up to 4 days. Reheat them gently on the stove or slow cooker so the cheese doesn’t overcook.

These can also be frozen in a freezer-safe container for up to 2 months. Thaw them in the fridge overnight before reheating.

Meatballs topped with melted cheese in a slow cooker, with a wooden spoon lifting several meatballs; herbs and a blue checkered cloth are nearby.

Variations And Add-ins

Cheese: Swap Gruyere with provolone, Swiss, or mozzarella for a different cheesy topping.
Appetizers: Make them party-style by serving on toothpicks with extra cheese melted over the top.
Serving options: Serve over egg noodles, mashed potatoes, or even cauliflower mash for a lower-carb dinner idea.
Meatballs sub: For a meatball sub, pile them into a crusty French roll and broil with Gruyere on top.

A bowl of meatballs topped with melted cheese and garnished with chopped parsley, placed on a table with a blue and white napkin and fresh herbs in the background.

Tips And Tricks

Slice your onions evenly so they caramelize at the same rate in the slow cooker.
Stir once or twice while cooking to help keep the meatballs coated in the savory sauce.
If the sauce is too thin, whisk in a little extra cornstarch slurry at the end.
Shred your Gruyere from a block instead of buying pre-shredded for the best melty results. I love using my KitchenAid shredder attachment for this!

A plate of mashed potatoes topped with meatballs in brown gravy, garnished with chopped parsley. Bread, fresh parsley, and a blue-checkered napkin are nearby.

FAQs

Can I use homemade meatballs instead of frozen?

Absolutely! Just make sure they’re cooked through before adding them to the slow cooker. Cooking them from raw in the slow cooker may produce too much juice so I would cook them first.

Why are my onions still crunchy?

Be patient, they just need more time. Keep cooking until soft and caramelized, or slice them thinner next time.

Can I prep this the night before?

Sure. You can slice onions and mix the sauce ahead, then store in the fridge. When ready to cook, just layer everything in the crockpot and press start.

Can I add wine to the sauce?

You can but it’s not required. A splash of dry white wine adds a little depth and makes the sauce taste more like classic French onion soup. Just don’t add too much or the sauce will be too thin.

A fork holds a meatball over a plate of mashed potatoes topped with meatballs, brown gravy, sliced onions, and chopped parsley.

More Easy Meatball Recipes

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Lisa, author of Fun Money Mom, standing in front of a kitchen counter with a cupcake.

About Lisa O’Driscoll

Lisa O’Driscoll is a lifestyle and parenting expert, cookbook author, and the creative force behind Fun Money Mom, a popular blog she’s Lisa O’Driscoll is a lifestyle and parenting expert, cookbook author, and the creative force behind Fun Money Mom, a popular blog she’s run since 2014. She’s the author of the children’s cookbook Roll It, Slice It, Mash It, Dice It, designed to get kids excited about cooking. With multiple TV appearances under her belt, she loves sharing her expertise on family-friendly recipes, creative DIYs, and party planning and is always on a mission to inspire and entertain!

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