Crockpot French Onion Meatballs (Easy Slow Cooker Recipe)

These Crockpot French onion meatballs are an easy dump-and-go recipe made with frozen meatballs, rich onion gravy, and melted Gruyère cheese. Simply add everything to the slow cooker, let the meatballs heat through, then thicken the sauce and finish them with a layer of melted cheese.

Serve these French onion meatballs over mashed potatoes, rice, or noodles for an easy dinner, or set them out with toothpicks as a warm party appetizer. They cook in about two hours with no thawing, browning, or stovetop preparation required.

Love the rich, savory flavor of French onion dishes? Try my French Onion Hamburger Steak or French Onion Meatloaf for two more comforting dinner ideas.

Ingredient Tips

Frozen meatballs

Use fully cooked frozen meatballs so they can go directly into the slow cooker without thawing. Beef meatballs work especially well with the French onion flavors, but turkey or homestyle meatballs can also be used.

Condensed French onion soup

The canned soup provides the softened onions and concentrated onion flavor for the sauce. Using the onions already in the soup keeps this recipe quick while still giving the meatballs the texture associated with French onion dishes.

Onion soup mix

A packet of onion soup mix strengthens the savory onion flavor. French onion soup mix can be used when available, but Lipton onion soup mix or beefy onion soup mix will also work. Choose the beefy onion version when possible for a deeper flavor.

Beef broth

Beef broth thins the condensed soup and creates enough sauce to coat the meatballs. Low-sodium broth gives you more control over the salt level.

Water can be substituted without making the sauce bland because the canned soup and seasoning packet already contain plenty of beef and onion flavor.

Cornstarch slurry

Mix cornstarch with cold water before adding it to the slow cooker. The slurry thickens the cooking liquid into a gravy-like sauce that clings to the meatballs.

Stir the slurry again immediately before pouring it in because cornstarch settles quickly.

Gruyère cheese

Gruyère adds the nutty, savory flavor commonly associated with French onion soup. Grate it from a block for the smoothest melting.

Mozzarella can be substituted for a milder and more affordable topping. Provolone is another good option if you prefer its flavor.

Fresh thyme

Fresh thyme is optional, but it adds color and a light herbal finish that balances the rich onion gravy and melted cheese.

How to Make French Onion Meatballs in the Crock Pot

Add the meatballs

Place the frozen fully cooked meatballs directly into the slow cooker. There is no need to thaw or brown them first.

Make the French onion sauce

In a bowl, whisk together the condensed French onion soup, onion soup mix, and beef broth until combined.

Pour the mixture over the frozen meatballs, then gently stir so the meatballs are coated in the sauce.

Cook the meatballs

Cover the slow cooker and cook on high for 2 hours, or until the meatballs are hot throughout.

Thicken the sauce

Mix the cornstarch with cold water until smooth. Stir the slurry again immediately before adding it because the cornstarch can settle at the bottom.

Pour the slurry into the slow cooker and gently stir it into the sauce. The sauce should begin thickening almost immediately. If needed, leave the slow cooker on high for another 5 to 10 minutes.

Add the cheese

Turn off the slow cooker or reduce it to the warm setting if you plan to serve the meatballs shortly.

Sprinkle the grated Gruyère evenly over the meatballs, cover, and let it melt for about 10 minutes.

Garnish with fresh thyme and serve warm.

Frequently Asked Questions (FAQs)

What to Serve With Crockpot French Onion Meatballs

These French onion meatballs can be served as either an easy dinner or a warm appetizer.

For dinner, spoon the meatballs and onion gravy over mashed potatoes, egg noodles, rice, or creamy polenta. The sauce also pairs well with roasted vegetables, green beans, Brussels sprouts, or a simple side salad.

For an appetizer, keep the meatballs warm in the slow cooker and serve them with toothpicks. Add sliced baguette or dinner rolls on the side for soaking up the extra French onion gravy.

Because the meatballs are rich and savory, simple sides work best and allow the onion sauce and melted Gruyère to remain the focus.

How to Store and Reheat

Storing leftovers

Allow the meatballs to cool, then transfer them and the sauce to an airtight container. Refrigerate for up to 4 days.

The Gruyère will firm up once chilled, but it will melt back into the sauce as the meatballs are reheated.

Reheating

Reheat individual portions in the microwave until the meatballs are hot throughout. Stir the sauce halfway through so it heats evenly.

For a larger amount, return the meatballs to the slow cooker and heat on low until warmed through. Add a small splash of beef broth or water if the sauce has become thicker during refrigeration.

Avoid reheating them on high for an extended period because the fully cooked meatballs may dry out.

Can you freeze French onion meatballs?

Yes. The meatballs and onion sauce can be frozen for up to 2 months, but the cheese topping may become grainy after thawing.

For the best results, freeze the meatballs and sauce without the Gruyère. Thaw them overnight in the refrigerator, reheat until hot, then add freshly grated cheese and cover until melted.

More Easy Meatball Recipes

Keep dinner simple or find your next party appetizer with these easy meatball recipes.

• 26 ounce frozen fully cooked meatballs
• 10.5 ounce can condensed French onion soup
• 1 packet French onion soup mix
• 1 cup low-sodium beef broth or water
• 1 cup Gruyere cheese grated
• fresh thyme for garnish

For thickening (cornstarch slurry)

• 1/4 cup cold water
• 2 tablespoon cornstarch

• Place the frozen meatballs directly into the slow cooker. There is no need to thaw them first.

• In a bowl, whisk together the condensed French onion soup, onion soup mix, and beef broth until combined.

• Pour the French onion mixture over the meatballs and gently stir to coat them in the sauce.

• Cover and cook on high for 2 hours, or until the meatballs are hot throughout.

• In a small bowl, stir together the cornstarch and cold water until smooth. Stir the slurry again immediately before adding it to prevent settled cornstarch from remaining at the bottom.

• Pour the slurry into the slow cooker and gently stir it into the sauce. The sauce should begin thickening quickly. Continue cooking on high for 5 to 10 minutes if needed.

• Turn off the slow cooker or reduce it to the warm setting.

• Sprinkle the grated Gruyère evenly over the meatballs. Cover and allow the cheese to melt for about 10 minutes.

• Garnish with fresh thyme and serve warm.

• Use fully cooked frozen meatballs for this recipe. Raw frozen meatballs may require a different cooking time and additional food-safety precautions.
• The onions in the condensed French onion soup provide the best texture for this short cooking time. Raw onions will not have enough time to caramelize and develop the flavor traditionally associated with French onion soup.
• French onion soup mix can sometimes be difficult to find. Regular onion soup mix will work, but use beefy onion soup mix when available for a deeper beef flavor.
• Water can be substituted for the beef broth. The condensed soup and seasoning packet provide enough beef and onion flavor to keep the sauce from tasting bland.
• Mozzarella can be substituted for Gruyère for a milder and more affordable cheese topping. Provolone will also work.
• To cook on low, cover and cook for approximately 3 to 4 hours, or until the meatballs are hot throughout. Add the slurry and cheese near the end as directed.