French Onion Meatballs

French Onion Meatballs with caramelized onions, rich beef gravy, and melty Gruyère make a cozy, cheesy comfort dinner everyone will love.

Course Main Course

Cuisine French

Keyword Baked Meatballs

Prep Time 15

Cook Time 2

Total Time 2 15

Servings -15 large meatballs

Calories 274kcal

Author Kathleen

3 tablespoons butter
2 tablespoons olive oil
6 cups sliced yellow onions, about 3 large
3/4 teaspoon fine salt, add mid-way through caramelizing
1/4 cup dry sherry Marsala, or dry white wine (for deglazing — optional but highly recommended)
3 tablespoons all-purpose flour
2 tablespoons tomato paste
1 tablespoon Worcestershire sauce
2 cups beef stock, plus more as needed
1 teaspoon Better Than Bouillon beef base
4 sprigs fresh thyme or 2 teaspoons dried thyme
1/2 teaspoon sherry vinegar or red wine vinegar to finish
1 tablespoon black pepper or to taste
1 cup shredded Gruyère cheese or half Gruyère, half mozzarella for creamier melt

In a heavy-bottomed pot or Dutch oven, melt the butter and olive oil over medium heat. Add all the sliced onions, stir to coat, and cover. Cook for 30 minutes, stirring occasionally.
Remove the lid, reduce heat to low, and add 1/2 teaspoon fine salt. Continue cooking 30–45 minutes, stirring every 10 minutes until the onions are deep golden brown and jammy.
Deglaze the pan with ¼ cup dry sherry (or white wine), scraping up any browned bits. Simmer until almost evaporated.
Reserve ½ cup of the onions for the meatballs.
Sprinkle the remaining onions with flour and tomato paste, stirring constantly for 3–4 minutes until lightly browned and fragrant.
Stir in Worcestershire sauce, beef stock, Better Than Bouillon (if using), thyme, and black pepper.
Simmer uncovered for 25–30 minutes to develop flavor and thicken slightly. Remove thyme stems.
Stir in vinegar at the end to brighten the flavor. Keep warm on low heat.

Preheat oven to 400°F (204ºC).
In a large mixing bowl, combine milk, egg, Pecorino, salt, pepper, parsley, garlic, and bread. Mash into a soft paste (panade) and let rest for 5 minutes to fully absorb.
Add ground beef (and pork, if using) along with the ½ cup chopped caramelized onions.
Using your hands, gently mix just until combined — do not overwork the meat.
Form into 2-ounce meatballs (about golf-ball size) and arrange on a parchment-lined baking sheet.
Bake for 20 minutes, or until cooked through (internal temperature 160°F).

Parmesan Rind Magic: Add a Parmesan rind to the sauce while simmering for 20 minutes, then remove before serving. It infuses the sauce with nutty depth.
Flavor Boost: The splash of vinegar or Dijon mustard at the end cuts through the richness perfectly.
Serving Idea: These are fantastic over creamy mashed potatoes, buttered noodles, or toasted baguette rounds — just like a deconstructed bowl of French onion soup.