In a large mixing bowl, combine ground beef, breadcrumbs, minced garlic, eggs, and a generous sprinkle of salt and pepper.

Once the meat mixture is ready, take small amounts and roll them into 1-inch meatballs, placing them onto a baking sheet.

In a large skillet, melt a tablespoon of butter over medium heat. Add thinly sliced onions, cooking them gently for 15–20 minutes until golden brown.

In the slow cooker, add the caramelized onions, then pour in beef broth and soy sauce, sprinkling in dried thyme.

Gently place the rolled meatballs into the sauce mixture in the slow cooker, ensuring they are well-coated.

Cover the slow cooker and set it to cook on low for 6 hours or high for 3 hours.