01 -
Preheat oven to 200°C. Combine ground beef, breadcrumbs, Parmesan cheese, parsley, egg, minced garlic, onion powder, salt, and pepper in a large mixing bowl. Mix thoroughly, then shape into 1.5-inch meatballs. Arrange on a parchment-lined baking sheet.
02 -
Bake in the preheated oven for approximately 20 minutes until browned and fully cooked. Remove and set aside.
03 -
Heat olive oil and butter in a large skillet over medium heat. Add sliced onions and cook, stirring occasionally, until caramelized (about 15-20 minutes). Stir in balsamic vinegar, beef broth, and thyme. Bring to a simmer and cook for an additional 5 minutes.
04 -
Reduce oven temperature to 175°C. Transfer baked meatballs to a large baking dish. Pour the French onion sauce over the meatballs, then sprinkle evenly with shredded Gruyère cheese.
05 -
Bake for 10-15 minutes until cheese is melted and bubbly. Remove from oven, garnish with fresh parsley, and serve warm.