Ingredients:

  • 2 lbs Ground Beef (80/20 suggested)
  • 1/2 cup Panko Breadcrumbs
  • 1 large Egg, lightly beaten
  • 2 Tbsp Milk (whole or 2%)
  • 1 Tbsp Worcestershire Sauce
  • 1 tsp Dried Thyme
  • 1/2 tsp Garlic Powder
  • Salt & Black Pepper, to taste
  • 3 large Yellow Onions, thinly sliced
  • 2 Tbsp Unsalted Butter
  • 2 cups Beef Broth (low sodium)
  • 1/4 cup Dry Sherry or Dry White Wine (optional)
  • 1 tsp Dijon Mustard
  • 6 oz Gruyère Cheese, shredded or thinly sliced
  • 2 Tbsp Fresh Parsley, chopped (for garnish)

Instructions:

  1. In a small skillet, melt butter over medium heat. Add the thinly sliced onions and a pinch of salt. Cook slowly, stirring occasionally, for about 15–20 minutes until deeply softened and starting to brown slightly.
  2. In a large bowl, gently combine the ground beef, Panko, beaten egg, milk, Worcestershire sauce, thyme, garlic powder, salt, and pepper. Mix lightly; do not overmix.
  3. Roll the mixture into uniform 1.5-inch balls (approximately 24 meatballs).
  4. Lightly spray the slow cooker insert. Spread half of the sautéed onions across the bottom. Arrange the raw meatballs on top in a single layer.
  5. Whisk together the beef broth, dry sherry/wine (if using), and Dijon mustard. Pour this liquid evenly over the meatballs. Top with the remaining onions.
  6. Cover and cook on Low for 6–8 hours or on High for 3–4 hours, until the meatballs are fully cooked (internal temperature should reach 160°F/71°C).
  7. If the sauce seems too thin, carefully remove the meatballs, turn the Crock Pot to High, and mix 1 tablespoon of cornstarch with 2 tablespoons of cold water. Whisk this slurry into the hot liquid and cook until thickened (about 15 minutes).
  8. Return the meatballs to the sauce. Top generously with the Gruyère cheese. Cover and cook on High for the last 15–20 minutes, or until the cheese is beautifully melted and bubbly.
  9. Garnish with fresh parsley and serve immediately with crusty bread.